Aptamer methods and compositions

ABSTRACT

Methods of selecting an aptamer that specifically binds to a target molecule complexed with a derivatization agent. Also disclosed are specific aptamers and methods of use thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation in Part of InternationalApplication No. PCT/US14/29281 filed 14 Mar. 2014, which claims thebenefit of U.S. Provisional Application Ser. No. 61/798,079 filed 15Mar. 2013, each of which is incorporated herein by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant numbersCBET-1033288 and CBET-1026592 awarded by National Science Foundation.The government has certain rights in the invention.

MATERIAL INCORPORATED-BY-REFERENCE

The Sequence Listing, which is a part of the present disclosure,includes a computer readable form comprising nucleotide and/or aminoacid sequences of the present invention. The subject matter of theSequence Listing is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Systematic evolution of ligands by exponential enrichment (SELEX) is acombinatorial technique in molecular biology for producingoligonucleotides of either single-stranded DNA or RNA that specificallybind to a target ligand or ligands. Such conventional procedures can bebased on isolating binders from large libraries of random syntheticoligonucleotides. This method can produce strong binding aptamers to adesired ligand, but some ligands (e.g., glucose) have no known aptamers.This may occur because such molecule has no chemically functional groupsthat will bind the nucleotides. For example, there are no suitableaptamers (e.g., small, practical to synthesize, with high affinity)against sugars such as glucose, fatty acids or related long-chainlipids, or amino acids such as glycine or leucine.

SUMMARY OF THE INVENTION

Provided herein are methods and compositions for determining amino acidsin dilute-and-measure assays directly.

Among the various aspects of the present disclosure is the provision ofmethods and compositions for determining amino acids indilute-and-measure assays directly from bodily fluids through aptamericsensor/derivatization, complexation, and host-guest complex formation.

One aspect provides a method for isolating an aptamer. In someembodiments, the method includes providing a target molecule; providinga derivatization agent; contacting the target molecule and thederivatization agent to form a target complex; providing anoligonucleotide library comprising a plurality of aptamer candidates;contacting the target complex and the oligonucleotide library; andisolating an aptamer that binds to the target complex.

In some embodiments, isolating the aptamer that binds to the targetcomplex comprises removal of aptamer candidates that do not bind to thetarget complex. In some embodiments, the method includes eluting theaptamer from the bound target complex under increasing stringency, andisolating an eluted aptamer having high affinity for the target complex.In some embodiments, the method includes systematic evolution of ligandsby exponential enrichment (SELEX).

In some embodiments, the aptamer does not substantially bind thenon-complexed target molecule. In some embodiments, the aptamer does notsubstantially bind the non-complexed derivatization agent. In someembodiments, the method includes counter-selecting an aptamer againstthe derivatization agent alone or against the target molecule alone.

In some embodiments, the oligonucleotide library includes randomlygenerated oligonucleotide sequences of a fixed length flanked by aconstant 5′ end and a constant 3′ end, the constant 5′ end and theconstant 3′ end functioning as a primer.

In some embodiments, the aptamer is a DNA, RNA, or XNA molecule. In someembodiments, the aptamer comprises at least about 15 oligonucleotides upto about 100 oligonucleotides. In some embodiments, the aptamer has anequilibrium constant (Kd) of about 1 pM up to about 10.0 μM; about 1 pMup to about 1.0 μM; about 1 pM up to about 100 nM; about 100 pM up toabout 10.0 μM; about 100 pM up to about 1.0 μM; about 100 pM up to about100 nM; or about 1.0 nM up to about 10.0 μM; about 1.0 nM up to about1.0 μM; about 1 nM up to about 200 nM; about 1.0 nM up to about 100 nM;about 500 nM up to about 10.0 μM; or about 500 nM up to about 1.0 μM.

In some embodiments, the target molecule comprises a small molecule, aprotein, or a nucleic acid. In some embodiments, the target moleculecomprises a small molecule selected from the group consisting of acarbohydrate molecule, a fatty acid molecule, a steroid molecule, anamino acid, a lead-like small molecule, a drug-like small molecule, anda derivative or a combination thereof. In some embodiments, the targetmolecule comprises a carbohydrate molecule selected from the groupconsisting of glucose, dextrose, fructose, galactose, sucrose, maltose,lactose, polyol, polyhydric alcohol, polyalcohol, glycitol, methanol,glycol, glycerol, erythritol, threitol, arabitol, xylitol, ribitol,mannitol, sorbitol, galactitol, fucitol, iditol, inositol, volemitol,isomalt, maltitol, lactitol, maltotriitol, maltotetraitol, andpolyglycitol.

In some embodiments, the target molecule comprises a fatty acid moleculeselected from the group consisting of caprylic acid, capric acid, lauricacid, myristic acid, palmitic acid, stearic acid, arachidic acid,behenic acid, lignoceric acid, cerotic acid, myristoleic acid,palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenicacid, linoleic acid, linoelaidic acid, a-linolenic acid, arachidonicacid, eicosapentaenoic acid, erucic acid, and docosahexaenoic acid, orderivatives thereof. In some embodiments, the target molecule comprisesa steroid molecule selected from the group consisting of a cholestane, acholane, a pregnane, an androstane, a gonane, an estrane, cholesterol,estradiol, testosterone, progesterone, medrogestone, β-sitosterol, anddexamethasone. In some embodiment, the target molecule comprises asphingolipid, such as sphinganine, sphingosine, phosphorylatedsphingosine (e.g., sphingosine-1-phosphate), or methylated sphingosine,or a ceramide or sphingomyelin or ganglioside or phosphosphingolipid.

In some embodiments, the target molecule comprises an amino acidselected from the group consisting of histidine, isoleucine, leucine,lysine, methionine, phenylalanine, threonine, tryptophan, valine,alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid,glutamine, glycine, proline, serine, tyrosine, selenocysteine,pyrrolysine, lanthionine, 2-aminoisobutyric acid, dehydroalanine,N-formylmethionine, gamma-amino-butyric acid (GABA), hydroxyproline,carnitine, ornithine, S-adenosylmethionine, citrulline, beta alanine(3-aminopropanoic acid), canavanine, mimosine, aspartame,5-hydroxytryptophan, L-dihydroxyphenylalanine, and eflornithine.

In some embodiments, the derivatization agent comprises a metal ioncomplex, a cyclic oligosaccharide, a boronic acid, or a resorcinolcyclic tetramer. In some embodiments, the target molecule comprises anamino acid and the derivatization agent comprises a metal ion complex.In some embodiments, the target molecule comprises a fatty acid, asteroid, a hydrophobic lead-like compound, or a hydrophobic drug-likecompound and the derivatization agent comprises a cyclicoligosaccharide. In some embodiments, the target molecule comprises acarbohydrate and the derivatization agent comprises a boronic acid.

In some embodiments, the derivatization agent comprises Cp*Rh(III) or ametal ion complex selected from Ni(II), Cu(II), Zn(II), or Co(III) boundto a bidentate, tridentate, or tetradentate ligand. In some embodiments,the derivatization agent comprises a cyclic oligosaccharide, the cyclicoligosaccharide comprising a cyclodextrin derivative. In someembodiments, the derivatization agent comprises a boronic acid, theboronic acid comprising a bis-boronic acid, an aromatic boronic acid, anamino boronic acid, or an aromatic amino boronic acid.

In some embodiments, the method includes isolating an aptamer that bindsto the target complex and has a nucleic acid sequence comprising one ormore unpaired nucleic acid bases when the aptamer is folded into adouble stranded configuration, wherein the one or more unpaired nucleicacid bases form a binding pocket such that the aptamer can bind thederivatization agent and the target molecule.

Another aspect provides an aptamer. In some embodiments, the aptamer hasa nucleic acid sequence that includes SEQ ID NO: 3; SEQ ID NO: 4(Glucose-BA_01); SEQ ID NO: 5 (Glucose-BA_07); SEQ ID NO: 6(Glucose-BA_08); SEQ ID NO: 7 (Glucose-BA_09); SEQ ID NO: 8(Glucose-BA_10); SEQ ID NO: 9 (Glucose-BA_11); SEQ ID NO: 10(Glucose-BA_12); SEQ ID NO: 11 (Glucose-BA_13); SEQ ID NO: 12(Glucose-BA_14); SEQ ID NO: 13 (Glucose-BA_15); SEQ ID NO: 14(Glucose-BA_16); SEQ ID NO: 15 (Glucose-BA_17); SEQ ID NO: 16 (GLUBA02);SEQ ID NO: 17 (GLUBA09); SEQ ID NO: 18 (GLUBA09_M1); SEQ ID NO: 19(GLUBA17); SEQ ID NO: 20 (GLUBAN3W10); SEQ ID NO: 21 (GLUBAN3W11); orSEQ ID NO: 22 (GLUBAN3W19), or a sequence at least 80% (e.g., at least85%, 90%, 95%, 99%) identical thereto and binding glucose complexed witha bis-boronic derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 23 (FrucBA02); SEQ ID NO: 24 (FrucBA02_M1); or SEQID NO: 25 (FrucBA05), or a sequence at least 80% (e.g., at least 85%,90%, 95%, 99%) identical thereto and binding fructose complexed with abis-boronic derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 26 (GalacBA05); SEQ ID NO: 27 (GalacBA01); or SEQ IDNO: 28 (GalacBA06), or a sequence at least 80% (e.g., at least 85%, 90%,95%, 99%) identical thereto and binding galactose complexed with abis-boronic derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 29 (BAOnly01); or SEQ ID NO: 30 (BAOnly03), or asequence at least 80% (e.g., at least 85%, 90%, 95%, 99%) identicalthereto and binding boronic acid.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 31; SEQ ID NO: 32 (Arginine-Cp*Rh_02); SEQ ID NO: 33(Arginine-Cp*Rh_03); SEQ ID NO: 34 (Arginine-Cp*Rh_04); SEQ ID NO: 35(Arginine-Cp*Rh_05); or SEQ ID NO: 36 (ARG01_Cp), or a sequence at least80% (e.g., at least 85%, 90%, 95%, 99%) identical thereto and bindingarginine complexed with a Cp*Rh(III) derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 37 (AspaCp01); SEQ ID NO: 38 (AspaCp03); or SEQ IDNO: 39 (AspaCp04), or a sequence at least 80% (e.g., at least 85%, 90%,95%, 99%) identical thereto and binding asparagine complexed with aCp*Rh(III) derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 40 (CIT30NO2_Cp*Rh), or a sequence at least 80%(e.g., at least 85%, 90%, 95%, 99%) identical thereto and bindingcitrulline complexed with a Cp*Rh(III) derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 41 (GlutaCp02); or SEQ ID NO: 42 (GlutaCp15), or asequence at least 80% (e.g., at least 85%, 90%, 95%, 99%) identicalthereto and binding glutamine complexed with a Cp*Rh(III) derivatizationagent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 43; SEQ ID NO: 44 (Glycine-Cp*Rh_01); SEQ ID NO: 45(Gly-Cp); SEQ ID NO: 46 (Gly-Cp+1 bp); or SEQ ID NO: 47 (GLYHW-Cp*Rh06),or a sequence at least 80% (e.g., at least 85%, 90%, 95%, 99%) identicalthereto and binding glycine complexed with a Cp*Rh(III) derivatizationagent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 48 (LeuCp01); SEQ ID NO: 49 (LeuCp04); or SEQ ID NO:50 (LeuCp17), or a sequence at least 80% (e.g., at least 85%, 90%, 95%,99%) identical thereto and binding leucine complexed with a Cp*Rh(III)derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 51 (LysCp05); or SEQ ID NO: 52 (LysCp*Rh18), or asequence at least 80% (e.g., at least 85%, 90%, 95%, 99%) identicalthereto and binding lysine complexed with a Cp*Rh(III) derivatizationagent

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 53 (PACp*Rh01); SEQ ID NO: 54 (PACp*Rh02); SEQ IDNO: 55 (PACp*Rh03); or SEQ ID NO: 56 (HPheAl04), or a sequence at least80% (e.g., at least 85%, 90%, 95%, 99%) identical thereto and bindingphenylalanine complexed with a Cp*Rh(III) derivatization agent

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 73 (Cu(II)_Phe01); SEQ ID NO: 74 (Cu(II)-Phe10); orSEQ ID NO: 75 (Cu(II)-Phe10_49 nt), or a sequence at least 80% (e.g., atleast 85%, 90%, 95%, 99%) identical thereto and binding phenylalaninecomplexed with a Cu(II) derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 57 (HTrp03), or a sequence at least 80% (e.g., atleast 85%, 90%, 95%, 99%) identical thereto and binding tryptophancomplexed with a Cp*Rh(III) derivatization agent;

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 57 (HTrp03), or a sequence at least 80% (e.g., atleast 85%, 90%, 95%, 99%) identical thereto and binding tryptophancomplexed with a Cp*Rh(III) derivatization agent; or

In some embodiments, the aptamer has a nucleic acid sequence thatincludes SEQ ID NO: 58; SEQ ID NO: 59 (Tyrosine-Cp*Rh_02); SEQ ID NO: 60(Tyrosine-Cp*Rh_03); SEQ ID NO: 61 (Tyrosine-Cp*Rh_04); SEQ ID NO: 62(Tyrosine-Cp*Rh_05); SEQ ID NO: 63 (Tyrosine-Cp*Rh_06); SEQ ID NO: 64(Tyrosine-Cp*Rh_07); SEQ ID NO: 65 (Tyrosine-Cp*Rh_08); SEQ ID NO: 66(Tyrosine-Cp*Rh_09); SEQ ID NO: 67 (Tyrosine-Cp*Rh_10); SEQ ID NO: 68(Tyrosine-Cp*Rh_11); SEQ ID NO: 69 (Tyrosine-Cp*Rh_12); SEQ ID NO: 70(Tyrosine-Cp*Rh_13); SEQ ID NO: 71 (Tyr-Cp*Rh (38nt)); or SEQ ID NO: 72(HTyrs07), or a sequence at least 80% (e.g., at least 85%, 90%, 95%,99%) identical thereto and binding tyrosine complexed with a Cp*Rh(III)derivatization agent.

In some embodiments, the aptamer has a nucleic acid sequence thatincludes one or more unpaired nucleic acid bases when the aptamer isfolded into a double stranded configuration. In some embodiments, theone or more unpaired nucleic acid bases form a binding pocket such thatthe aptamer can bind a derivatization agent and a target molecule. Insome embodiments, the aptamer has a nucleic acid sequence that includesSEQ ID NO: 71 (Tyr-Cp*Rh(38nt)); SEQ ID NO: 53 (PACp*Rh01); SEQ ID NO:40 (CIT30NO2_Cp*Rh); SEQ ID NO: 41 (GlutaCp02); SEQ ID NO: 52(LysCp*Rh18); SEQ ID NO: 51 (LysCp05); SEQ ID NO: 75 (Cu(II)-Phe10_49nt); SEQ ID NO: 36 (ARG01_Cp); SEQ ID NO: 57 (HTrp03 aptamer); SEQ IDNO: 45 (Gly-Cp); SEQ ID NO: 38 (AspaCp03); SEQ ID NO: 47(GLYHW-Cp*Rh06); SEQ ID NO: 50 (LeuCp17); SEQ ID NO: 53 (PACp*Rh01); SEQID NO: 73 (Cu(II)_Phe01); or SEQ ID NO: 56 (HPheAl04); or a sequence atleast 80% (e.g., at least 85%, 90%, 95%, 99%) identical thereto andbinding the target molecule complexed with the derivatization agent.

Another aspect provides a method of detecting a target molecule in asample. In some embodiments, the method includes (a) providing a sample;(b) contacting the biological sample and a derivatization agent to forma target complex comprising the derivatization agent and a targetmolecule when the target molecule is present in the sample; (c)contacting the biological sample and (i) an aptamer selected accordingto methods described above or (ii) an aptamer described above to form anaptamer target complex when the target complex is present in the sample;and (d) detecting the aptamer target complex when present in the sample.

Other objects and features will be in part apparent and in part pointedout hereinafter.

DESCRIPTION OF THE DRAWINGS

Those of skill in the art will understand that the drawings, describedbelow, are for illustrative purposes only. The drawings are not intendedto limit the scope of the present teachings in any way.

FIG. 1A is an illustration of a generic scheme of complexation between areceptor (e.g., organometallic or synthetic receptor) and its target(e.g., small molecules target). FIG. 1B is an illustration of a genericscheme of complexation between a receptor (e.g., organometallic receptorincluding metal and organic ligand) and its target (e.g., DNA), withfurther binding of enhanced aptamer. FIG. 1C is an illustration of theselection, where the targeting receptor is in the presence of a largeexcess of target. FIG. 1D is similar to FIG. 1A with 30N. FIG. 1E showsequilibrium relationship between receptor and target.

FIG. 2 is an illustration of the mechanism for a Cp*Rh(III) complex usedto in situ derivatize all bi- and tri-dentate ligands, such as aminoacids, amino sugars, peptides, diols. Also illustrated is Cp*Rh(III)complex binding to arginine.

FIG. 3A-FIG. 3F is a series of chemical structures and line and scatterplots showing the detection of tyrosine in dilute-and-measure assay atclinically relevant concentrations. FIG. 3A is a chemical structure oftyrosine. FIG. 3B is an illustration of a motif isolated that binds toCp*Rh(III)*Tyr, with conserved bases in bold. FIG. 3C is an illustrationof the structure of sensors (where F represents fluorescein and Drepresents dabcyl) used to obtain results in FIG. 3D-F. FIG. 3D is aline and scatter plot of a sensor responding to concentrations oftyrosine in the presence of Cp*Rh(III) at constant 10 μM concentration.FIG. 3E is a line and scatter plot showing a sensor is selective fortyrosine over various other amino acids in the presence of 50 μMCp*Rh(III) and aptamer sensors. FIG. 3F is a line and scatter plot ofthe sensor in serially diluted 1 mM tyrosine solution (blue), serumspiked with 1 mM tyrosine, then diluted (red), and healthy, fastingsubject serum (black). A 10 μM concentration of Cp*Rh(III) was added toall samples to derivatize all bi- and tri-dentate ligands. At certaindilutions the difference between spiked and non-spiked serums wereobserved, despite presence of all interferences. The data shows thattyrosine can be detected in a dilute-and-measure assay.

FIG. 4A-FIG. 4J is a series of chemical structures and line and scatterplots showing the detection of arginine in dilute-and-measure assay atclinically relevant concentrations. FIG. 4A is a chemical structure ofarginine. FIG. 4B is an illustration of a motif isolated that binds toCp*Rh(III)*Arg, with conserved bases in bold. FIG. 4C is an illustrationof the structure of sensors (where F represents fluorescein and Drepresents dabcyl) used to obtain results in FIG. 4D-F. FIG. 4D is aline and scatter plot of a sensor responding to concentrations ofarginine in the presence of Cp*Rh(III) at constant 50 μM concentration.FIG. 4E is a line and scatter plot showing a sensor is selective forarginine over various other amino acids in the presence of 50 μMCp(Rh(III) and aptameric sensor. FIG. 4F is a line and scatter plot ofthe sensor in serially diluted 1 mM arginine solution (blue), serumspiked with 1 mM arginine, then diluted (red), and healthy, fastingsubject serum (black). A 10 μM concentration of Cp*Rh(III) was added toall samples to derivatize all bi- and tri-dentate ligands. At certaindilutions the difference between spiked and non-spiked serums wereobserved, despite presence of all interferences. The data shows thatarginine can be detected in a dilute-and-measure assay at clinicallyrelevant concentrations. FIG. 4G shows a motif isolated that binds toCp*Rh(III)*Phe with Kd of about 60 nm. FIG. 4H shows a motif that bindsPhe (i.e., without cofactor) with Kd of about 6 μM. FIG. 4I shows RFU asa function of amino acid (Phe, Trp, Tyr) concentration for the motif ofFIG. 4G. FIG. 4J shows RFU as a function of amino acid (Phe)concentration for the motif of FIG. 4H.

FIG. 5A is an illustration of the mechanism of the complexation ofShinkai's sensor, an example of boronic acid-based sensing of glucose(or other sugars), with glucose (presented as a sphere). FIG. 5B is anillustration of an example of an aptamer that binds only to glucose.FIG. 5C is an illustration of the structure of sensor based on theaptamer in FIG. 5B (where F represents fluorescein and D representsdabcyl). FIG. 5D is a line and scatter plot showing response of thesensor of FIG. 5C to BA only or BA-Glu. FIG. 5E is a line and scatterplot showing response of the sensor of FIG. 5C to Glu only or BA-GluFIG. 5F is a plot showing the response of the sensor of FIG. 5C bindingto glucose at 520 correlated with the response of the same sensorbinding to glucose at 427 nm. FIG. 5G is a line and scatter plot showingthe response of the sensor from FIG. 5C to glucose and other sugars, inthe presence of 50 μM Shinkai's sensor. FIG. 5H is a line and scatterplot showing the response to boronic acid sensor (Shinkai's) in thepresence and absence of 40 mM glucose. FIG. 5I illustrates an aptamersensor, which is shown specific for glucose in FIG. 5L. FIG. 5Jillustrates an aptamer sensor, which is shown specific for fructose inFIG. 5M. FIG. 5K illustrates an aptamer sensor, which is shown specificfor galactose in FIG. 5N.

FIG. 6A-FIG. 6B are line and scatter plot comparisons of selectivity andsensitivity of a (Shinka's) boronic acid sensor with and withoutaptamer.

FIG. 7A-FIG. 7H are a series of chemical structures showing aptamershaving at least one unpaired base forming a pocket that binds a metalcomplex or an amino acid target molecule. FIG. 7A shows a metalcomplex/ion binding motif for an aptamer that binds nucleic acids. FIG.7B shows Tyr selective aptamer Tyr-Cp*Rh(38nt) (SEQ ID NO: 71). FIG. 7Cshows Phe cross-reactive Trp aptamer PACp*Rh01 (SEQ ID NO: 53). FIG. 7Dshows citrulline non-selective aptamer CIT30NO2_Cp*Rh (SEQ ID NO: 40).FIG. 7E shows Gln selective aptamer GlutaCp02 (SEQ ID NO: 41). FIG. 7Fshows Lys non-selective aptamer LysCp*Rh18 (SEQ ID NO: 52). FIG. 7Gshows Lys selective aptamer LysCp05 (SEQ ID NO: 51). FIG. 7H shows Phecross-reactive Trp aptamer Cu(II)-Phe10_49 nt (SEQ ID NO: 75).

FIG. 8A-FIG. 8C is a series of chemical structures showing aptamershaving at least two unpaired bases forming a pocket that binds a metalcomplex or an amino acid target molecule. FIG. 8A shows the bindingmotif for a plurality of unpaired bases. FIG. 8B shows Arg selectiveARG01_Cp aptamer (SEQ ID NO: 36). FIG. 8C shows Trp selective HTrp03aptamer (SEQ ID NO: 57).

FIG. 9A-FIG. 9C is a series of chemical structures showing aptamershaving a plurality of unpaired bases forming a pocket that binds a metalcomplex or an amino acid target molecule. FIG. 9A shows Gly selectiveaptamer Gly-Cp sensor (SEQ ID NO: 45). FIG. 9B shows Asn selectiveaptamer AspaCp03 (SEQ ID NO: 38). FIG. 9C shows Gly non-specific aptamerGLYHW-Cp*Rh06 (SEQ ID NO: 47).

FIG. 10A-FIG. 10B is a series of chemical structures showing multiplefolding configurations of LeuCp17 aptamer (SEQ ID NO: 50) selective forLeu over Ile having a plurality of unpaired bases forming a plurality ofpockets (compare FIG. 10A and FIG. 10B), one of more of which pocketscan bind a metal complex and also an amino acid target molecule. ACp*Rh(III) can bind more than one site, such as additional G's that canbe targeted.

FIG. 11A-FIG. 11B is a chemical structure of PACp*Rh01 aptamer (SEQ IDNO: 53) reactive for Phe and cross-reactive for Trp and a scatter andline plot showing use thereof. FIG. 11A depicts the structure of anaptamer reactive for Phe and cross-reactive for Trp. FIG. 11B is ascatter and line plot showing aptamer detected Phe concentration (μM) asa function of time (hr) in serum samples from capillary blood of afemale subject (TPW) and a male subject (MNS) having an oral load of 100mg/kg at time zero.

FIG. 12A-FIG. 12D is a series of aptamer structures and scatter and lineplots showing use thereof. FIG. 12A shows Cu(II)_Phe01 aptamer (SEQ IDNO: 73) reactive for Phe. FIG. 12B shows a scatter and line plot for RFUas a function of amino acid concentration (μM) for phenylanine,tyrosine, tryptophan, and glycine using the aptamer of FIG. 12A, wherePhe specificity is demonstrated. FIG. 12C shows HPheAl04 aptamer (SEQ IDNO: 56) reactive for Phe. FIG. 12D shows a scatter and line plot for RFUas a function of amino acid concentration (μM) for phenylanine,tryptophan, and tyrosine, using the aptamer of FIG. 12C, where Phespecificity is demonstrated.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is based, at least in part, on the discovery ofaptamers against boronic acid-sugar complexes and amino acid-Cp*Rh(III)complexes. Described herein is in situ derivatization SELEX forisolation of high-affinity and high-specificity, low complexityaptameric sensors (see Examples). Thus is provided an ability to detectin solution-phase difficult to measure analytes.

According to approaches described herein, one can perform in situderivatization of challenging targets with known organic receptors(e.g., a metal ion complex, such as Cp*Rh(III), for amino acids;cyclodextrin derivatives for fatty acids; boronic acids for glucose orother sugars) and perform selection that can target specificallycomplexes with these receptors, yielding high-affinity aptamers.

For example, a mixture of nucleic acid molecules (e.g., candidateaptamers, such as a library of DNA molecules) are allowed to bind atarget molecule (e.g., a protein, peptide, or small molecule displayingnucleophilic groups) in the presence of a derivatization agent, such asan organometallic reagent (e.g., modified Cp*Rh or Pt complexes), wherethe derivatization agent binds both a nucleic acid molecule and thetarget molecule. Tight multicomponent complexes can be isolated andamplified through standard protocols (e.g., SELEX). The identifiedaptamer can be useful as a tightly binding analytical reagent.

Accordingly, both derivatization agents or targets themselves can beselected against during selection of the complex. These procedures canyield aptamers against challenging targets where conventional approacheswould likely fail.

Conventional approaches, such as systematic evolution of ligands byexponential enrichment (SELEX), are not always effective againstchallenging targets having no chemically functional groups that willbind nucleotides. The present disclosure can provide for functionalaptamers for challenging targets. Aptamers selected according to thepresent disclosure can be obtained by complexing in situ a target ligandwith various metal ions, sugars, or acids. Such an approach allows forsuccessful production of aptamers for challenging targets, e.g., glucoseor amino acids, as described herein. Compositions and methods describedherein can be useful, for example, in clinical chemistry or for controlof nucleic acid-based nanostructures.

In some embodiments, a nucleic acid molecule (e.g., DNA) in the presenceof organometallic compound is coordinated by metal, while organiccomponents stick out. If a library of DNA molecules is present, memberswill form many complexes in equilibrium. Organic components oforganometallic complex, remaining valences (coordination sites) onmetal, and nucleic acid molecule (e.g., DNA) all can then form a complexwith target. Such a complex can be isolated in conventional ways (e.g.,traditional or solution-phase SELEX). A result can be a nucleic acidaptamer (e.g., DNA) that is enhanced in binding by organometalliccomponents. Two or more organometallic components can bind in anaptamer, and many different complexes can be used at the same time inmixtures.

Aptamers, or oligonucleotide-based receptors as described herein,provide unique advantages as analytical tools. For example, an aptamercan be incorporated in simple and rapid mix-and-measure assays orreadily attached to a surface e.g., suitable for integration inbiosensors.

The present disclosure provides the ability to determine amino acids indilute-and-measure assay directly from bodily fluids through aptamericsensor/in-situ derivatization protocol. Some embodiments provide methodsfor determination of amino acids or other bi- and tri-dentate analytesin dilute-and-measure assays using in situ derivatization withorganometallic reagents and aptameric sensors specific for particularderivatives. Prior to the present disclosure, there was thought to be nogenerally available and easy to use specific, quantitatively suitableassay. Conventionally, amino acids were determined in complex multi-stepprocedures requiring specialized instrumentation. The present disclosurecan overcome these limitations and others, such as interferences,associated with conventional approaches.

Approaches described herein can introduce complexity to a targetmolecule and specifically target the resulting derivatized target toselect a small to medium aptamer; as opposed to selecting a large,complex aptamer against a simple target or pre-incorporating (i.e.,co-opting) a cofactor (e.g., an organic receptor) inside the aptamer(which may not yield increase, and would likely lead to a decrease, ofsensitivity of original receptor because binding of aptamer to receptormight compete with binding of ligand to receptor).

Derivatization Agent

As described herein, a derivatization agent can be combined with atarget molecule to form in situ a complex capable of binding an aptamer.In some embodiments, an aptamer can bind two or more derivatizationagents (see e.g., FIG. 1F). In some embodiments, two or morederivatization agents and resulting complexes can be included in amixture. The complex can be stable or in equilibrium with freederivatization agent and target analyte.

A derivatization agent can be a metallic, organic, or an organometallicreceptor. For example, a derivatization agent can be a metal ion, metalion complex, a cyclic oligosaccharide, or a boronic acid.

Metal ion or metal ion complex.

A derivatization agent can include a metal ion or metal ion complex. Ametal ion or metal ion complex derivatization agent can be complexedwith an amino acid to select an aptamer thereto. For example, a metalion complex derivatization agent (e.g., Cp*Rh(III)) can be complexedwith glycine to select an aptamer thereto. As another example, a metalion complex derivatization agent (e.g., Cp*Rh(III)) can be complexedwith tyrosine to select an aptamer thereto. As another example, a metalion derivatization agent (e.g., Cu(II)) can be complexed withphenylalanine to select an aptamer thereto.

For example, a derivatization agent can include or be Ni(II), Cu(II),Zn(II), Co(III), Pt or most any other metal, optionally with abidentate, tridentate, or tetradentate ligand binding to it (e.g.,Co(II) with tetradentate ligand) (see generally, Chin et al. 1999 Nature401(6750), 254-257; Job et al. 1974 J. Am. Chem. Soc. 96, 809-819;Yamaguchi et al. 1980 Inorg. Chem. 19, 2010-2016; Fenton et al. 1995Inorg. Chim. Acta 236, 109-115; Greenstein et al. 1996 Chemistry of theAmino Acids Vol. 1, 594, Wiley and Sons, New York). For example, aderivatization agent can be Ni(II), Cu(II), Zn(II), Co(III), or most anyother metal, with a bidentate, tridentate, or tetradentate ligandbinding to it. As another example, a metal ion derivatization agent canbe Cu(II). As another example, a derivatization agent can include ametal ion complex comprising an alkali metal (e.g., lithium, sodium,potassium, rubidium, cesium, or francium), an alkaline earth metal(e.g., beryllium, magnesium, calcium, strontium, barium, or radium), atransition metal (e.g., zinc, molybdenum, cadmium, scandium, titanium,vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium,zirconium, niobium, technetium, ruthenium, rhodium, palladium, silver,hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold,mercury, rutherfordium, dubnium, seaborgium, bohrium, hassium, orcopernicium), a post-transition metal (e.g., aluminum, gallium, indium,tin, thallium, lead, bismuth, or polonium), a lanthanide metal (e.g.,lanthanum, cerium, praseodymium, neodymium, promethium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, or lutetium), an actinide metal (e.g., actinium, thorium,protactinium, uranium, neptunium, plutonium, americium, curium,berkelium, californium, einsteinium, fermium, mendelevium, nobelium, orlawrencium), or another type of metal (e.g., meitnerium, darmstadtium,roentgenium, ununtrium, flerovium, ununpentium, livermorium, germanium,arsenic, antimony, or astatine). The metal ion can be bound to abidentate, tridentate, or tetradentate ligand to form a derivatizationagent. Ligands suitable for binding a metal are known in the art. Anexemplary ligand is a cyclopentadienyl or a pentamethylcyclopentadienyl.

Organic or Organometallic Component.

A derivatization agent can include an organic or organometalliccomponent. The metal ion can be bound to a bidentate, tridentate, ortetradentate ligand to form a derivatization agent. Ligands suitable forbinding a metal are known in the art. An exemplary ligand is acyclopentadienyl (Cp) or a pentamethylcyclopentadienyl (Cp*). Thepentamethylcyclopentadienyl ligand (Cp*) is a ligand in organometalliccompounds arising from the binding of the five ring-carbon atoms inC₅Me₅-, or Cp*-, to metals.

For example, a metal ion complex derivatization agent can be Cp*-X,where X is a metal (e.g., Rh). For example, a metal ion complexderivatization agent can be Cp*Rh(III) (see e.g., Example 2; Example 3).

As another example, a metal ion complex derivatization agent can beCp-X, where X is a metal and CP is cyclopentadienyl or a Cp derivative.

As another example, a metal ion complex derivatization agent can be anFp2 or Fp2-X (e.g., where Fp2 is a fip dimer, cyclopentadienylirondicarbonyl dimer, Cp₂Fe₂(CO)₄).

Linker.

A derivatization agent can have a linker between the metal ion and theorganic component. A linker can be, for example, an organic moleculewith at least one end having a functional group. Various linker groupsare known in the art; except as otherwise specified, compositionsdescribed herein can include state of the art linker groups. Forexample, a state of the art linker molecule can be any such moleculecapable of coupling a metal ion and an organic component. A linker groupcan include one or more of the following exemplary functional groups:carboxylic acid or carboxylate groups (e.g.,Fmoc-protected-2,3-diaminopropanoic acid, ascorbic acid), silane linkers(e.g., aminopropyltrimethoxysilane (APTMS)), or dopamine. A linkergroup, such as carboxylic acid, dopamine, or silane (or another state ofthe art linker group), can provide missing coordination sites (e.g., twooxygen coordination sites) for binding. Exemplary linking groupsinclude, but are not limited to, carboxylic acid or carboxylate groups,Fmoc-protected-2,3-diaminopropanoic acid, ascorbic acid, silane linkers,aminopropyltrimethoxysilane (APTMS), or dopamine. Other linkers caninclude alkane, alkene, or alkyne linkers of various size (e.g., n=2, 3,4, 5, 6, 7, 8, 9, or 10, or more). A linker can include chemical motifssuch as disulfides, hydrazones, or peptides (e.g., cleavable), orthioethers (e.g., noncleavable). A linker can include maleimide, orsulfhydryl reactive groups, or succinimidyl esters.

For example, a metal ion complex derivatization agent can beCp*-CH_(2(n))X, where X is a metal (e.g., a metal described above) and nis at least 1 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more). —CH₂ linkersof various lengths can be used. As another example, a metal ion complexderivatization agent can be Cp*-CH₂CH₂X, where X is a metal (e.g., ametal described above).

Cyclic Oligosaccharide.

A derivatization agent can be a cyclic oligosaccharide. A derivatizationagent can be a cyclodextrin or cyclodextrin derivative. A derivatizationagent can be a cyclic oligosaccharide with hydrophobic cavities. Forexample, a derivatization agent can be an α-cyclodextrin (i.e., asix-membered sugar ring molecule), a β-cyclodextrin (i.e., aseven-membered sugar ring molecule), or a γ-cyclodextrin (i.e., aneight-membered sugar ring molecule), or a derivative thereof. Aderivatization agent can be a cyclodextrin derivative. For example, aderivatization agent can be an α-cyclodextrin, a β-cyclodextrin, or aγ-cyclodextrin having on either or both rims one or hydroxyl groupsderivatized with other groups. Availability of multiple reactivehydroxyl groups can be used to increase functionality of a cyclodextrinby substituting them (i.e., derivatizing them).

A cyclodextrin or cyclodextrin derivative can have at least 5glucopyranoside (e.g., α-D-glucopyranoside) units linked 1, 4. Forexample, a cyclodextrin or cyclodextrin derivative can have 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, 30, 31, 32, or more, glucopyranoside units.

A derivatization agent can be a cyclodextrin derivative. A cyclodextrinderivative can be, for example, an α-cyclodextrin, a β-cyclodextrin, ora γ-cyclodextrin. For example, a derivatization agent can be anα-cyclodextrin, a β-cyclodextrin, or a γ-cyclodextrin having on eitheror both rims one or hydroxyl groups displayed. Availability of multiplereactive hydroxyl groups can increase functionality of a cyclodextrin.Functional groups used to derivatize hydroxyl groups can contain basicgroups, such as imidazoles, pyridines, metal ion complexes, acidicgroups, such as carboxylic acids, sulfates, or photoreactive groups. Acyclic oligosaccharide derivatization agent can be complexed with, forexample, a fatty acid, steroid, or hydrophobic drug to select an aptamerthereto. In some embodiments, a cyclic oligosaccharide derivatizationagent can be complexed with a fatty acid to select an aptamer thereto.

Organoborane.

A derivatization agent can be an organoborane. A derivatization agentcan be a boronic acid. A boronic acid is understood to be an alkyl oraryl substituted boric acid containing a carbon-boron bond and isunderstood to belong to the larger class of organoboranes. In someembodiments, a boronic acid can form reversible covalent complexes withmolecules such as sugars, amino acids, hydroxamic acids, etc., ormolecules with Lewis base donor functional groups such as alcohol,amine, or carboxylate. The chemistry involved in binding a boronic acidto a target molecule, such as a saccharide, is understood in the art andcan be adapted accordingly for use described herein (see generally, Fanget al. 2004 J Fluorescence 14(5), 481-489).

Exemplary boronic acids suitable as a derivatization agent include, butare not limited to an aromatic boronic acid or amino boronic acid. Anaromatic boronic acid can includes phenyl, naphty, anthrylboronic acids,pyrenyl, or any other aromatic group. A boronic acid or an aromaticboronic acid can further include an amino group. For example, anaromatic boronic acid can have an amino group is positioned in a1,5-relationship with the boronic acid.

A derivatization agent comprising a boronic acid can include more thanone boronic acid group or an aromatic boronic acid can include more thanone boronic acid group or more than one aromatic group. For example, twoaromatic acids can be connected via a linker or boronic, e.g., asdepicted below.

An exemplary boronic acid derivatization agent can be:

The above exemplary boronic acid derivatization agent can interact witha sugar, such as glucose, as follows:

As described herein, a boronic acid derivatization agent can becomplexed with a sugar to select an aptamer thereto. For example, aboronic acid derivatization agent can be complexed with glucose toselect an aptamer thereto. As another example, a bis-boronic receptorcan be a derivatization agent complexed with glucose to select anaptamer thereto (see e.g., Example 4, FIG. 5).

Target Molecule

As disclosed herein, a target molecule can be combined with aderivatization agent to form a complex, and an aptamer can be raisedagainst such complex. A target molecule can be, for example, a smallmolecule, a protein, or a nucleic acid, or structures or compositionscontaining any of these. For example, a target molecule can be aprotein, peptide, or small molecule displaying one or more nucleophilicgroups. As another example, a target molecule can be a small moleculeselected from a carbohydrate molecule, a fatty acid molecule, an aminoacid, or a derivative or a combination thereof.

A target molecule can occur in solution or attached to a substrate. Forexample, a target molecule can be a sugar molecule on the surface of acell.

Amino Acid Target Molecule.

A target molecule can be an amino acid or an analog or derivativethereof. Shown herein is analysis of specific amino acids (e.g.,tyrosine and arginine) by in situ derivatization with Cp*Rh(III) and anaptamer measuring the complex formation (see e.g., Example 2; Example3). For example, an amino acid target molecule can be complexed with ametal ion derivatization agent (e.g., Cp*Rh(III)) and an aptamer can beselected against such complex. Results showed an unexpected extremelyhigh affinity selection. Such high affinity is sufficient for serumanalysis and demonstrates a novel and unexpected dilute-and-measureassay of amino acids.

An amino acid is understood as an organic compound having amine (—NH₂)and carboxylic acid (—COOH) functional groups, along with a side-chainspecific to each amino acid. A target molecule can be any of the about500 known amino acids (see generally, W et al. 1983 Chem. Int. Ed. Engl.22(22), 816-828). A target molecule can be an alpha- (α-), beta- (β-),gamma- (γ-) or delta- (δ-) amino acid. A target molecule can be analiphatic, acyclic, aromatic, hydroxyl-containing, or sulfur-containingamino acid. An amino acid analog or derivative can be, for example, anamino alcohol or an aminophosphonic acid.

A target molecule can be a proteinogenic amino acid. For example, atarget molecule can be an amino acid selected from histidine,isoleucine, leucine, lysine, methionine, phenylalanine, threonine,tryptophan, valine, alanine, arginine, asparagine, aspartic acid,cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine,selenocysteine, or pyrrolysine. As another example, a target moleculecan be tyrosine (see e.g., Example 2). As another example, a targetmolecule can be arginine (see e.g., Example 3).

A target molecule can be an essential amino acid, such as histidine,isoleucine, leucine, lysine, methionine, phenylalanine, threonine,tryptophan, or valine.

A target molecule can be a non-essential amino acid, such as alanine,arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine,glycine, ornithine, proline, serine, or tyrosine.

A target molecule can be a non-proteinogenic amino acid. For example, atarget molecule can be an amino acid selected from lanthionine,2-aminoisobutyric acid, dehydroalanine, N-formylmethionine,gamma-amino-butyric acid (GABA), hydroxyproline, carnitine, ornithine,S-adenosylmethionine, citrulline, beta alanine (3-aminopropanoic acid),canavanine, mimosine, or aspartame.

A target molecule can be an amino acid derivative, such as5-hydroxytryptophan, L-dihydroxyphenylalanine, or eflornithine.

In some embodiments, the target molecule can be an amino acid and thecorresponding binding aptamer has a nucleic acid sequence with one ormore unpaired bases such that a metal complex can bind a pocket formedby the one or more unpaired bases and also binds the target amino acid.For example, the following formulas depict a binding site formed by theG-A mismatch surrounded by binding base pairs (e.g., G-C, G-T, A-T, A-Uor analogs).

An unbound nucleic acid pocket can appear in a folding program (seee.g., FIG. 7B-FIG. 7E). An unbound nucleic acid pocket does not have toappear in a folding program but can be recognized by its sequences(compare FIG. 7F-G). An unbound nucleic acid pocket can bind Cp*Rh(compare FIG. 7B-G), but can also bind other metals (compare Cu2+ inFIG. 7H).

Sugar Target Molecule.

Shown herein is highly specific glucose sensing by a nucleic acidaptamer (see e.g., Example 4). Results showed an unexpected highaffinity of selected aptamers. This is in contrast to prior conventionalapproaches which have been unable to select an aptamer that recognizedglucose.

A target molecule can be a sugar. A target molecule can be acarbohydrate. A target molecule can be a saccharide. A target moleculecan be a monosaccharide, including but not limited to glucose, dextrose,fructose, or galactose. For example, a target molecule can be glucose(see e.g., Example 4). As another example, a glucose target molecule canbe complexed with a boronic acid derivatization agent (e.g., bis-boronicacid) and an aptamer can be selected against such complex.

A target molecule can be a disaccharide, including but not limited tosucrose (glucose and fructose), maltose (glucose and glucose), orlactose (galactose and glucose). A target molecule can be a hydrogenatedform of carbohydrate, whose carbonyl group (aldehyde or ketone, reducingsugar) has been reduced to a primary or secondary hydroxyl group. Atarget molecule can be a sugar alcohol, such as a polyol, polyhydricalcohol, polyalcohol, or glycitol. A target molecule can be a sugaralcohol, such as methanol, glycol, glycerol, erythritol, threitol,arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol,iditol, inositol, volemitol, isomalt, maltitol, lactitol, maltotriitol,maltotetraitol, or polyglycitol, or disaccharide combinations thereof.For example, an aptamer raised against a complex of erythritol complexedwith a derivatization agent can be used to detect erythritol excreted inurine of a subject.

Lipid Target Molecule.

As described herein, an aptamer can be raised against a lipid targetmolecule, such as fatty acids, steroids, sphingollipids, orphospholipids complexed with a derivatization agent.

For example, an aptamer can be raised against a fatty acid moleculecomplexed with a cyclodextrin derivative derivatization agent. A fattyacid is understood as a carboxylic acid with a long aliphatic tail(chain), which is either saturated or unsaturated. A target molecule canbe a naturally-occurring fatty acid molecule. A target molecule can be anaturally-occurring fatty acid molecule having at least about 4 up toabout 28 carbon atoms. A target molecule can be a fatty acid moleculederived from a monoglyceride, diglyceride, triglyceride, phospholipid,sphingolipid, or ganglioside. A target molecule can be a free fatty acidmolecule.

A target molecule can be a short-chain fatty acid (e.g., fatty acid withaliphatic tails of fewer than six carbons, such as butyric acid); amedium-chain fatty acid (e.g., a fatty acid with aliphatic tails of 6-12carbons, which can form medium-chain triglycerides); a long-chain fattyacid (e.g., fatty acids with aliphatic tails 13 to 21 carbons); or verylong chain fatty acids (e.g., fatty acids with aliphatic tails longerthan 22 carbons).

A target molecule can be a saturated fatty acid molecule. For example, atarget molecule can be a saturated fatty acid molecule selected fromcaprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,stearic acid, arachidic acid, behenic acid, lignoceric acid, or ceroticacid, or derivatives thereof.

A target molecule can be an unsaturated fatty acid molecule. Forexample, a target molecule can be an unsaturated fatty acid moleculeselected from myristoleic acid, palmitoleic acid, sapienic acid, oleicacid, elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid,a-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid,or docosahexaenoic acid, or derivatives thereof. As another example, atarget molecule can be an unsaturated fatty acid molecule selected fromlinolenic acid (LA), a-linolenic acid (ALA), eicosapentaenoic acid(EPA), or docosahexaenoic acid (DHA).

A target molecule can be a steroid molecule. A steroid is understood asa type of organic compound containing a characteristic arrangement offour cycloalkane rings joined to each other. A target molecule can be,for example, a steroid molecule selected from a cholestane, a cholane, apregnane, an androstane, a gonane, or an estrane. A target molecule canbe, for example, a steroid molecule selected from cholesterol,estradiol, testosterone, progesterone, medrogestone, β-sitosterol, ordexamethasone.

A target molecule can be a sphingolipid or a phospholipid. For example,a target molecule can be a sphingosine-phosphate, sphingomyeline,ganglioside, or phosphatidyl-choline.

Other Small Molecules.

A target molecule can be a small molecule. As described herein, anaptamer can be raised against a small molecule complexed with aderivatization agent. A small molecule target having relatively fewnative features that would otherwise raise a large or complex aptamercan be especially suited for the approach described herein. For example,a target molecule can be a catechol (e.g., dopamine and L-DOPA(L-3,4-dihydroxyphenylalanine)).

A target molecule can be a lead-like small molecule or a drug-like smallmolecule. For example, a target molecule can be a hydrophobic lead-likeor a hydrophobic drug-like molecule. A lead-like small molecule isgenerally understood to have a relatively smaller scaffold-likestructure (e.g., molecular weight of about 150 to about 350 kD) withrelatively fewer features (e.g., less than about 3 hydrogen donorsand/or less than about 6 hydrogen acceptors; hydrophobicity characterxlogP of about −2 to about 4) (see e.g., Angewante (1999) Chemie Int.ed. Engl. 24, 3943-3948). In contrast, a drug-like small molecule isgenerally understood to have a relatively larger scaffold (e.g.,molecular weight of about 150 to about 500 kD) with relatively morenumerous features (e.g., less than about 10 hydrogen acceptors and/orless than about 8 rotatable bonds; hydrophobicity character xlogP ofless than about 5) (see e.g., Lipinski (2000) J. Pharm. Tox. Methods 44,235-249).

Formation of Complex

As described herein, formation of a complex between a target moleculeand a derivatization agent allows selection of a specific, high affinityaptamer to the complex.

A target molecule and a derivatization agent can be combined in anysuitable fashion (e.g., in solution) to allow the derivatization agentto derivatize (e.g., non-specifically) a functional group present. Forexample, a target molecule and a derivatization agent can be combined insolution to allow the derivatization agent to derivatize (e.g.,non-specifically derivatize) a functional group present (e.g., anyfunctional group present).

An aptamer can bind at high affinity to the complex of target moleculeand derivatization agent. In some embodiments, an aptamer does not bindto target molecule or derivatization agent alone.

In some embodiments an aptamer can bind to a derivatization agent withlesser affinity than to the complex of target molecule andderivatization agent. In some embodiments an aptamer can bind to atarget molecule with lesser affinity than to the complex of targetmolecule and derivatization agent. In some embodiments an aptamer canbind to a derivatization agent or target molecule with lesser affinitythan to the complex of target molecule and derivatization agent. In someembodiment, an aptamer does not substantially bind to a target moleculeand can bind to derivatization agent in a different conformation thanwith the complex.

In some embodiments, an aptamer may not form a stable stem in thepresence of derivatization agent, but can form a stable stem uponaddition of complex.

Thus is provided a novel and unexpected ability to dilute-and-measureanalyte.

Selection of Aptamer

Described herein is a direct protocol for isolation of high-affinityoligonucleotide-based sensors (e.g., aptameric) reporting smallmolecules complexed in situ with their synthetic receptors. Variousembodiments of the protocol can allow isolation of oligonucleotidesresponsive to targets that have previously resisted attempts to identifyaptamers against them (see e.g., Example 1). For example, using methodsdescribed herein, oligonucleotides responding to either high or lowconcentrations of glucose were selected, a result not previouslyachieved under conventional approaches (see e.g., Example 4).

Aptamer selection processes against unmodified target molecules are wellknown (see generally, Oliphant et al. 1989 Mol. Cell Biol. 9, 2944-2949;Tuerk and Gold 1990 Science 249, 505-510; Ellington and Szostak 1990Nature 346, 818-822). Such conventional processes include systematicevolution of ligands by exponential enrichment (SELEX); selected andamplified binding site (SAAB) or cyclic amplification and selection oftargets (CASTing). Except as otherwise noted herein, therefore, theprocess of the present disclosure can be carried out in accordance withsuch processes. For example, conventional aptamer selection techniquemay be used against the novel complex of a derivatization agent and atarget molecule (as described herein) rather than against merely theconventional non-modified target. For example, kinetic capillaryelectrophoresis can be used for the selection of aptamers (e.g., smartaptamers).

The present disclosure provides a viable alternative to a conventionalapproach of pursuing high affinity, high complexity receptors for simplesmall molecules. Rather, as described herein, it can be advantageous forisolation of suitable aptamers to increase the complexity of targets viain situ, dynamic, or reversible complexation of the target with aderivatization agent (e.g., a reversible derivatization agent). Suchcomplexation can provide additional epitopes for interactions withpotential aptamers and these aptamers can be less structurally complexgiven the added complexity of the target.

Furthermore, aptamers specifically binding to the complex can beisolated rather than those binding individual components of the complex.Thus is provided, in various embodiments, methods for identifying smallto medium sized aptamers against simple small molecules with otherwisefew epitopes by turning such simple small molecules into high affinityligands through derivatization.

Aptamer selection can include providing a large oligonucleotide library,e.g., of randomly generated sequences of fixed length flanked byconstant 5′ and 3′ ends that can serve as primers. Sequences in thelibrary can be exposed to a complex of a derivatization agent and atarget molecule, and those sequences that do not bind the target can beremoved (e.g., by affinity chromatography). Sequences can be eluted andamplified by PCR to prepare for subsequent rounds of selection in whichthe stringency of elution conditions can be increased to identifydesirable (e.g., tightest-binding) sequences.

In some embodiments, an RNA library can be used to omit the constantprimer regions (which may stabilize secondary structures that areunstable when formed by the random region alone), thereby increasingease of removal after the selection process because they stabilizesecondary structures that are unstable when formed by the random regionalone (see generally, Jarosch et al. 2006 Nucleic Acids Res 34(12),e86).

In some embodiments, explicit counter-selection of aptamers againstderivatization agent alone or against target molecule alone can beperformed.

Selections can be performed in a media containing a desired sample type(e.g., urine, serum, etc.) for both selection and counter-selection,which can minimize the variability of these matrices and account forinterferences. Selection conditions and added cofactors can increase theaffinity of aptamers (e.g., for amino acids without side-chains thatdisplay strong epitopes).

The present disclosure overcomes various problems with conventionalaptamer selection. One obstacle to broad conventional use of aptamers inbioanalysis is that various small molecule targets are missing epitopesthat can effectively interact with nucleic acids (e.g., hydrophobicsurfaces and positively charged functionalities), and this in turn leadsto the need for highly complex aptamers, inaccessible throughconventional SELEX protocols. For example, glucose is a small moleculefor which no aptamers have ever been reported in peer-reviewedliterature, despite its significance and commercial value.

Even where a small molecule target has some moiety against which, atleast in principle, an aptamer can be raised (e.g., naturally occurringoligonucleotide receptors against minimalist targets poor with epitopes,such as fluoride anion and glycine, see generally Mandal et al. 2004Science 306, 275-279; Baker et al. 2012 Science 335(6065), 233-235),such natural receptors have substantial informational complexity,measured by a number of bases needed to define their highly structuredbinding sites. Conventional approaches, such as in vitro selection andamplification (SELEX) methods used to select aptamers from randomoligonucleotide libraries, are not well suited for isolation ofstructurally complex aptamers. And, even when a conventionally selectedaptamer against a difficult small molecule target is available, itsaffinity can be too low to be analytically useful. Furthermore,conventional tools to optimize aptamer affinity are lacking (cf.affinity-maturation process for antibodies).

Various approaches described herein are distinguished from conventionalprotocols. Prior work involved use of organic synthetic receptors ascofactors for aptamers, in which a tartarate-citrate receptor based onboronic acid was incorporated in aptamers with a goal of impacting it'sselectivity (see e.g., Manimala et al. 2004 J. Am. Chem. Soc. 126,16515-16519). But a resulting aptamer-receptor complex in this priorstudy had lesser affinity to tartarate and citrate than the receptoritself, while its selectivity indeed changed due to these differentdrops in affinity. Furthermore, in that prior study, both receptor andreceptor target complexes induced similar conformational changes inaptamer at the equally low concentrations (20 μM), indicating similarbinding affinities.

Embodiments of the present disclosure differ from prior studies in atleast several ways.

In some embodiments, counter-selection of aptamers against aderivatization agent alone or against a target molecule alone can beused in, with, or after the process of aptamer selection for the complexof derivatization agent and target molecule (see e.g., FIG. 1). Acounter-selection step can disfavor incorporation of a receptor (e.g.,of the derivatization agent alone or the target molecule alone) into anaptameric sensor on its own or can lead to an increase of analyticalsensitivity or can lead to a different mode of sensing with cofactoralone. Reasoning supporting such as approach is at least as follows. Ifan aptamer incorporates a derivatization agent prior to its binding tothe target molecule, there may be no reason to assume thatfunctionalities in the derivatization agent that are binding to theaptamer will not be binding to the target molecule as well. In otherwords, binding to the derivatization agent alone may be competing withbinding to the target molecule, which may result in decreased affinity.If an aptamer binds substantially only to the complex of derivatizationagent and target molecule after such complex is formed, and if it bindstightly, it can stabilize formation even at very low concentration.Thus, in the presence of an excess of receptor, aptamer can detect andstabilize very low concentrations of ligands (i.e., target moleculescomplexed with derivatization agent).

In some embodiments, elution from a solid-state bound target is notperformed during selection. Rather, affinity elution can be performedfrom a library attached to a solid state with a target molecule, not viaa displacement of target molecule with a non-target from a complex oftarget molecule and derivatization agent. This change can avoidselection pressure against high-affinity interactions with a complex oftarget molecule and derivatization agent or can lead to an increase inaffinity.

Aptamer

As described herein, an aptamer can be identified against a complex of aderivatization agent and a target molecule. An aptamer, as the term isused herein, is understood as a nucleic acid species engineered throughrepeated rounds of selection (e.g., in vitro selection) to bind to atarget molecule, such as small molecules, proteins, nucleic acids,cells, tissues, or organisms.

For those small molecules for which aptamer have been previouslysuccessfully isolated, such as amino acids, various embodiments of themethod described herein can provide significantly superior affinity orreduced aptamer size, or both.

Before, during, or after recognition of a target molecule, an aptamercan bind by complementary nucleic acid base pairing, which can create asecondary structure, such as a short helical arm or a single strandedloop. A combination of these secondary structures can result in theformation of a tertiary structures, which can allow an aptamer to bindto a target molecule via van der Waals forces, hydrogen bonding, orelectrostatic interaction (similar to an antibody binding to anantigen). When such tertiary structure forms, some, most, or all of theaptamer can fold into a complex (e.g., a stable complex) with the targetmolecule forming an aptamer-target complex. This three-dimensionalstructure can allow an aptamer to function like an antibody, whichcontrasts to conventional thinking which held that polynucleic acidswere merely linear, information holding structures.

An aptamer can be a nucleic acid aptamer. An aptamer can be a DNAaptamer. A DNA aptamer can be relatively more stable, cheaper, andeasier to produce than an RNA aptamer. An aptamer can be an RNA aptamer.An RNA aptamer can have a relatively more diverse three-dimensionalstructure than a DNA aptamer. An aptamer can be an XNA aptamer. Anaptamer can be a smart aptamer, selected with a pre-defined equilibriumconstants (K_(d)), rate constants (k_(off), k_(on)), and thermodynamic(ΔH, ΔS) parameters of aptamer-target interaction.

An aptamer described herein can be modified, e.g., to resist degradationin a sample. For example, sugar modifications of nucleosidetriphosphates can render a resulting aptamer resistant to nucleasesfound in serum. As another example, changing a 2′OH group of ribose to a2′F or 2′NH₂ group can yield an aptamer having increased stability or alonger half-life, such as in blood-containing sample or in an in vitroor in vivo environment (see e.g., Brody and Gold 2000 Rev Molec Biol74(1), 5-13). As another example, conjugating an aptamer to a highermolecular weight vehicle can increase stability or half-life in an invitro or in vivo environment. As another example, an aptamer can beconjugated to a nanomaterial.

An aptamer as described herein can be at least about 15oligonucleotides. An aptamer as described herein can be up to about 100oligonucleotides. For example, an aptamer as described herein can be atleast about 15 oligonucleotides up to about 100 oligonucleotides. Asanother example, an aptamer as described herein can be at least about15, at least about 20, at least about 25, at least about 30, at leastabout 35, at least about 40, at least about 45, at least about 50, atleast about 55, at least about 60, at least about 65, at least about 70,at least about 75, at least about 80, at least about 85, at least about90, at least about 95, at least about 100, or more oligonucleotides. Itis understood that recitation of each of these individual valuesincludes ranges there between.

Nucleic acid sequences for exemplary aptamers are provided herein. It isunderstood that an aptamer can have a nucleic acid sequence according tothe discrete exemplary sequence provided, or a sequence at least 80%identical thereto (e.g., at least 85%, at least 90%, at least 91%, atleast 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98% or at least 99%) and binding (e.g., selective ornon-selective) a target molecule complexed with a derivatization agent.One of ordinary skill will understand that certain regions of theaptamer are more robust with respect to nucleic acid substitution. Forexample, stem regions of a secondary or tertiary structure of an aptamermay have reduced impact on target molecule binding, and so, nucleic acidsubstitutions in these regions can be more freely made. In contrast,secondary or tertiary structure regions of an aptamer associated withbinding to target molecules may be more sensitive, and so, may requiremore conservative substitutions or fewer substitutions. Similarly,regions of an aptamer important or critical to certain secondary ortertiary structural features may be more sensitive, and so, may requiremore conservative substitutions or fewer substitutions. In someembodiments, nucleic acid sequence identity can be lower in stem regions(e.g., at least about 80%, at least about 85%, or at least about 90%)compared to regions associated with binding a target molecule or regionsimportant or critical to secondary or tertiary structural features(e.g., at least about 90%, at least about 95%, or at least about 99%).

An aptamer as described herein can have an equilibrium constant Kd ofabout 1 pM up to about 100 μM. An aptamer having a Kd as low as about 1pM to about 100 pM can be with respect to a target molecule, such as asugar, natively on a surface, such as a cell surface. An aptamer asdescribed herein can have an equilibrium constant Kd of about 1 pM up toabout 10.0 μM. As another example, an aptamer as described herein canhave an equilibrium constant Kd of about 1 pM up to about 10.0 μM; about1 pM up to about 1.0 μM; about 1 pM up to about 100 nM; about 100 pM upto about 10.0 μM; about 100 pM up to about 1.0 μM; about 100 pM up toabout 100 nM; or about 1.0 nM up to about 10.0 μM; about 1.0 nM up toabout 1.0 μM; about 1 nM up to about 200 nM; about 1.0 nM up to about100 nM; about 500 nM up to about 10.0 μM; or about 500 nM up to about1.0 μM.

As another example, an aptamer as described herein can have anequilibrium constant Kd of about 1 pM, about 50 pM, about 100 pM, about150 pM, about 200 pM, about 250 pM, about 300 pM, about 350 pM, about400 pM, about 450 pM, about 500 pM, about 550 pM, about 600 pM, about650 pM, about 700 pM, about 750 pM, about 800 pM, about 850 pM, about900 pM, about 950 pM, about 1 nM, about 10 nM, about 20 nM, about 30 nM,about 40 nM, about 50 nM, about 60 nM, about 70 nM, about 80 nM, about90 nM, about 100 nM, about 110 nM, about 120 nM, about 130 nM, about 140nM, about 150 nM, about 160 nM, about 170 nM, about 180 nM, about 190nM, about 200 nM, about 250 nM, about 300 nM, about 350 nM, about 400nM, about 450 nM, about 500 nM, about 550 nM, about 600 nM, about 650nM, about 700 nM, about 750 nM, about 800 nM, about 850 nM, about 900nM, about 950 nM, about 1 μM, about 10 μM, about 20 μM, about 30 μM,about 40 μM, about 50 μM, about 60 μM, about 70 μM, about 80 μM, about90 μM, or about 100 μM. It is understood that ranges between differentcombinations of Kd listed above are contemplated.

Unpaired Bases.

An aptamer as described herein can have a nucleic acid sequence with oneor more unpaired nucleic acid bases. An aptamer with one or moreunpaired nucleic acid bases can form a binding pocket providing forbinding of the target molecule and the derivatization agent. Forexample, an aptamer with one or more unpaired nucleic acid bases canbind a derivatization agent and an amino acid target molecule. Asanother example, an aptamer with one or more unpaired nucleic acid basescan bind a metal ion complex derivatization agent (e.g., Cp*Rh(III)) andan amino acid target molecule. An example of a metal-complex bindingmotif of an aptamer with one or more unpaired nucleic acid bases andbinding of Cp*Rh(III) and an amino acid is as follows:

In the above motif, the binding site formed by the G-A mismatchsurrounded by binding base pairs (e.g., G-C, G-T, A-T, A-U or analogs).

Other examples of an aptamer with one or more unpaired nucleic acidbases are: Tyr selective aptamer Tyr-Cp*Rh(38nt) (SEQ ID NO: 71) asshown in FIG. 7B; Phe cross-reactive Trp aptamer PACp*Rh01 (SEQ ID NO:53) as shown in FIG. 7C; citrulline non-selective aptamer CIT30N02_Cp*Rh(SEQ ID NO: 40) as shown in FIG. 7D; Gln selective aptamer GlutaCp02(SEQ ID NO: 41) as shown in FIG. 7E; Lys non-selective aptamerLysCp*Rh18 (SEQ ID NO: 52) as shown in FIG. 7F; Lys selective aptamerLysCp05 (SEQ ID NO: 51) as shown in FIG. 7G; Phe cross-reactive Trpaptamer Cu(II)-Phe10_49 nt (SEQ ID NO: 75) as shown in FIG. 7H; Argselective ARG01_Cp aptamer (SEQ ID NO: 36) as shown in FIG. 8B; Trpselective HTrp03 aptamer (SEQ ID NO: 57) as shown in FIG. 8C; Glyselective aptamer Gly-Cp sensor (SEQ ID NO: 45) as shown in FIG. 9A; Asnselective aptamer AspaCp03 (SEQ ID NO: 38) as shown in FIG. 9B; Glynon-specific aptamer GLYHW-Cp*Rh06 (SEQ ID NO: 47) as shown in FIG. 9C;LeuCp17 aptamer selective for Leu over Ile (SEQ ID NO: 50) as shown inFIG. 10; PACp*Rh01 aptamer reactive for Phe and cross-reactive for Trp(SEQ ID NO: 53) as shown in FIG. 11A; Phe reactive Cu(II)_Phe01 aptamer(SEQ ID NO: 73) as shown in FIG. 12A; or Phe reactive HPheAl04 aptamer(SEQ ID NO: 56) as shown in FIG. 12C.

An unbound nucleic acid pocket can appear in a folding program (seee.g., FIG. 7B-E). An unbound nucleic acid pocket does not have to appearin a folding program but can be recognized by its sequences (compareFIG. 7F-G). An unbound nucleic acid pocket can bind Cp*Rh (compare FIG.7B-G), but can also bind other metals (compare Cu²⁺ in FIG. 7H).

Aptamers Specific for Monosaccharide-Derivatization Complex.

An aptamer as described herein can have a nucleic acid sequencecomprising SEQ ID NO: 3. An aptamer comprising SEQ ID NO: 3 can bind thetarget molecule glucose complexed with a bis-boronic derivatizationagent. Aptamers specific for the glucose-boronic acid complex can have anucleic acid sequence comprising: SEQ ID NO: 4 (Glucose-BA_01); SEQ IDNO: 5 (Glucose-BA_07); SEQ ID NO: 6 (Glucose-BA_08); SEQ ID NO: 7(Glucose-BA_09); SEQ ID NO: 8 (Glucose-BA_10); SEQ ID NO: 9(Glucose-BA_11); SEQ ID NO: 10 (Glucose-BA_12); SEQ ID NO: 11(Glucose-BA_13); SEQ ID NO: 12 (Glucose-BA_14); SEQ ID NO: 13(Glucose-BA_15); SEQ ID NO: 14 (Glucose-BA_16); SEQ ID NO: 15(Glucose-BA_17); SEQ ID NO: 16 (GLUBA02); SEQ ID NO: 17 (GLUBA09); SEQID NO: 18 (GLUBA09_M1); SEQ ID NO: 19 (GLUBA17); SEQ ID NO: 20(GLUBAN3W10); SEQ ID NO: 21 (GLUBAN3W11); or SEQ ID NO: 22 (GLUBAN3W19),or a sequence at least 80% identical thereto (e.g., at least 85%, atleast 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98% or at least 99%) andbinding (e.g., selective or non-selective) glucose complexed with abis-boronic derivatization agent.

Aptamers specific for the fructose-boronic acid complex can have anucleic acid sequence comprising: SEQ ID NO: 23 (FrucBA02); SEQ ID NO:24 (FrucBA02_M1); or SEQ ID NO: 25 (FrucBA05), or a sequence at least80% identical thereto (e.g., at least 85%, at least 90%, at least 91%,at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98% or at least 99%) and binding (e.g., selective ornon-selective) fructose complexed with a bis-boronic derivatizationagent.

Aptamers specific for the galactose-boronic acid complex can have anucleic acid sequence comprising: SEQ ID NO: 26 (GalacBA_05); SEQ ID NO:27 (GalacBA_01); or SEQ ID NO: 28 (GalacBA_06), or a sequence at least80% identical thereto (e.g., at least 85%, at least 90%, at least 91%,at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98% or at least 99%) and binding (e.g., selective ornon-selective) galactose complexed with a bis-boronic derivatizationagent.

Aptamers Binding to Boronic Acid.

Aptamers specific for boronic acid (e.g., a shinkai sensor) can have anucleic acid sequence comprising: SEQ ID NO: 29 (BAOnly01); or SEQ IDNO: 30 (BAOnly03), or a sequence at least 80% identical thereto (e.g.,at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98% or atleast 99%) and binding (e.g., selective or non-selective) boronic acid.

Aptamers Binding to Amino Acids.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) arginine complexed with a Cp*Rh(III) derivatizationagent. An aptamer as described herein can have a nucleic acid sequencecomprising SEQ ID NO: 31. An aptamer comprising SEQ ID NO: 13 can bindthe target molecule arginine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to an arginine-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 32 (Arginine-Cp*Rh_02); SEQID NO: 33 (Arginine-Cp*Rh_03); SEQ ID NO: 34 (Arginine-Cp*Rh_04); SEQ IDNO: 35 (Arginine-Cp*Rh_05); or SEQ ID NO: 36 (ARG01_Cp), or a sequenceat least 80% identical thereto (e.g., at least 85%, at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98% or at least 99%) and binding(e.g., selective or non-selective) arginine complexed with a Cp*Rh(III)derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) asparagine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to an asparagine -Cp*Rh(III) complex can havea nucleic acid sequence comprising: SEQ ID NO: 37 (AspaCp01); SEQ ID NO:38 (AspaCp03); or SEQ ID NO: 39 (AspaCp04), or a sequence at least 80%identical thereto (e.g., at least 85%, at least 90%, at least 91%, atleast 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98% or at least 99%) and binding (e.g., selective ornon-selective) asparagine complexed with a Cp*Rh(III) derivatizationagent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) citrulline complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to a citrulline-Cp*Rh(III) complex can have anucleic acid sequence comprising SEQ ID NO: 40 (CIT30NO2_Cp*Rh), or asequence at least 80% identical thereto (e.g., at least 85%, at least90%, at least 91%, at least 92%, at least 93%, at least 94%, at least95%, at least 96%, at least 97%, at least 98% or at least 99%) andbinding (e.g., selective or non-selective) citrulline complexed with aCp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) glutamine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to a glutamine-Cp*Rh(III) complex can have anucleic acid sequence comprising SEQ ID NO: 41 (GlutaCp02); or SEQ IDNO: 42 (GlutaCp15), or a sequence at least 80% identical thereto (e.g.,at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98% or atleast 99%) and binding (e.g., selective or non-selective) glutaminecomplexed with a Cp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) glycine complexed with a Cp*Rh(III) derivatizationagent. An aptamer as described herein can have a nucleic acid sequencecomprising SEQ ID NO: 43. An aptamer comprising SEQ ID NO: 43 can bindthe target molecule glycine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to an glycine-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 44 (Glycine-Cp*Rh_01); SEQID NO: 45 (Gly-Cp); SEQ ID NO: 46 (Gly-Cp+1 bp); or SEQ ID NO: 47(GLYHW-Cp*Rh 06), or a sequence at least 80% identical thereto (e.g., atleast 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98% or atleast 99%) and binding (e.g., selective or non-selective) glycinecomplexed with a Cp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) leucine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to a leucine-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 48 (LeuCp01); SEQ ID NO: 49(LeuCp04); or SEQ ID NO: 50 (LeuCp17), or a sequence at least 80%identical thereto (e.g., at least 85%, at least 90%, at least 91%, atleast 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 97%, at least 98% or at least 99%) and binding (e.g., selective ornon-selective) leucine complexed with a Cp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) lysine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to a lysine-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 51 (LysCp05); or SEQ ID NO:52 (LysCp*Rh18), or a sequence at least 80% identical thereto (e.g., atleast 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98% or atleast 99%) and binding (e.g., selective or non-selective) lysinecomplexed with a Cp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) phenylalanine complexed with a Cp*Rh(III)derivatization agent. An aptamer binding to a phenylalanine-Cp*Rh(III)complex can have a nucleic acid sequence comprising: SEQ ID NO: 53(PACp*Rh01); SEQ ID NO: 54 (PACp*Rh02); SEQ ID NO: 55 (PACp*Rh03); orSEQ ID NO: 56 (HPheAl04), or a sequence at least 80% identical thereto(e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 97%, at least98% or at least 99%) and binding (e.g., selective or non-selective)phenylalanine complexed with a Cp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) phenylalanine complexed with a Cu(II) derivatizationagent. An aptamer binding to a phenylalanine-Cu(II) complex can have anucleic acid sequence comprising: SEQ ID NO: 73 (Cu(II)_Phe01); SEQ IDNO: 74 (Cu(II)-Phe10); or SEQ ID NO: 75 (Cu(II)-Phe10_49 nt), or asequence at least 80% identical thereto (e.g., at least 85%, at least90%, at least 91%, at least 92%, at least 93%, at least 94%, at least95%, at least 96%, at least 97%, at least 98% or at least 99%) andbinding (e.g., selective or non-selective) phenylalanine complexed witha Cu(II) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) tryptophan complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to a tryptophan-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 57 (HTrp03), or a sequenceat least 80% identical thereto (e.g., at least 85%, at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98% or at least 99%) and binding(e.g., selective or non-selective) tryptophan complexed with aCp*Rh(III) derivatization agent.

An aptamer as described herein can bind (e.g., selectively ornon-selectively) tyrosine complexed with a Cp*Rh(III) derivatizationagent. An aptamer as described herein can have a nucleic acid sequencecomprising SEQ ID NO: 58. An aptamer comprising SEQ ID NO: 58 can bindthe target molecule tyrosine complexed with a Cp*Rh(III) derivatizationagent. An aptamer binding to an tyrosine-Cp*Rh(III) complex can have anucleic acid sequence comprising: SEQ ID NO: 59 (Tyrosine-Cp*Rh_02); SEQID NO: 60 (Tyrosine-Cp*Rh_03); SEQ ID NO: 61 (Tyrosine-Cp*Rh_04); SEQ IDNO: 62 (Tyrosine-Cp*Rh_05); SEQ ID NO: 63 (Tyrosine-Cp*Rh_06); SEQ IDNO: 64 (Tyrosine-Cp*Rh_07); SEQ ID NO: 65 (Tyrosine-Cp*Rh_08); SEQ IDNO: 66 (Tyrosine-Cp*Rh_09); SEQ ID NO: 67 (Tyrosine-Cp*Rh_10); SEQ IDNO: 68 (Tyrosine-Cp*Rh_11); SEQ ID NO: 69 (Tyrosine-Cp*Rh_12); SEQ IDNO: 70 (Tyrosine-Cp*Rh_13); SEQ ID NO: 71 (Tyr-Cp*Rh (38nt)); or SEQ IDNO: 72 (HTyrs07), or a sequence at least 80% identical thereto (e.g., atleast 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 97%, at least 98% or atleast 99%) and binding (e.g., selective or non-selective) tyrosinecomplexed with a Cp*Rh(III) derivatization agent.

Diagnostics

Aptamers described herein can be used in diagnostic applications.

Various embodiments of the method can address specific bioanalyticalneeds, such as mix-and-measure assays of diagnostic increases in smallmolecules in challenging biological matrices. The simplicity and generalapplicability of methods described herein or broad availability ofsynthetic receptors for small molecules provide applications of aptamersin clinical chemistry that have not been previously possible.

Conventional aptamer diagnostic protocols can be adapted by an artisanof ordinary skill for use with aptamers disclosed herein. Generally, anadditional step includes mixing a sample containing or suspected ofcontaining a target molecule with a derivatization agent so as to form acomplex. Such complex can then be detected with an aptamer disclosedherein according to a conventional assay. Thus is provided amix-and-measure modification that can be made to assays for detection ofsmall molecule targets in challenging biological matrices.

Aptamer usage in diagnostics is well known (see generally, Jayasena 1999Clin Chem 45(9), 1628-1650; Mascini 2009 Aptamers in Bioanalysis,Wiley-Interscience, 1^(st) Ed., ISBN-10: 0470148306). Except asotherwise noted herein, therefore, the process of the present disclosurecan be carried out in accordance with such processes.

An aptamer described herein can be immobilized on a surface suitable fordiagnostic applications, such as gold films, gold particles, silicates,silicon oxides, polymers, metallic substrates, biocoatings includingavidin or avidin derivatives, quantum dots, carbon nanotubes,superparamagnetic iron oxide nanoparticles, or carbohydrates (seegenerally, Balamurugan et al. 2008 Anal Bioanal Chem 390, 1009-1021;Famulok et al. 2007 Chemical Reviews 107(9), 3715-3743; see generally,Lee et al. 2010 Advanced Drug Delivery Systems 62(6), 592-605). Chemicalprotocols for covalent attachment of aptamers to functionalized surfacesis understood in the art and such protocols can be adapted for aptamersdisclosed herein. For example, an aptamer of the present disclosure canbe attached to a solid surface array.

An aptamer described herein can be used in conjunction with afluorescent, colorimetric, magnetic resonance imaging, orelectrochemical sensor or protocol (see generally, Lee et al. 2010Advanced Drug Delivery Systems 62(6), 592-605).

An aptamer described herein can be used to detect a target molecule in asample. A sample can be a biological sample. A sample can be abiological sample from a subject. The subject can be an animal subject,including a mammal, such as horses, cows, dogs, cats, sheep, pigs, mice,rats, monkeys, hamsters, guinea pigs, and chickens, and humans. Forexample, the subject can be a human subject.

A biological sample can be a fluid sample or a solid sample. Abiological sample can be a urine sample, a saliva sample, a bloodsample, a serum sample, a plasma sample, an amniotic fluid sample, acerebrospinal fluid sample, a sweat sample, an exhaled breath condensatesample, or a solid tissue sample. For example, the sample can be a bloodsample, such as a peripheral blood sample. As another example, a samplecan be a urine sample.

For example, an aptamer described herein can be used as an amino acidmarker. Such amino-acid specific aptamer can be used to detect an aminoacid in a biological sample (e.g., a urine sample).

An aptamer described herein can be used to detect a target moleculeassociated with a disease or condition. Diagnostic methods using anaptamer described herein can be performed on a subject having, diagnosedwith, suspected of having, or at risk for developing a disease orcondition associated with a target molecule. A determination of the needfor diagnosis can be assessed by a history and physical exam consistentwith the disease or condition at issue. Conventional diagnosticprotocols of a disease or disorder associated with a target molecule canbe adapted accordingly to use aptamers as disclosed herein.

Amino acids that are diagnostic or contribute to diagnosis for specificdisorders are known in the art (see generally, Blau 2004 Physician'sGuide to the Laboratory Diagnosis of Metabolic Diseases, 2d Ed.,Springer, ISBN-10: 354042542X). Methods described herein for isolatingan aptamer specific for an amino acid can be directed towards an aminoacid known to be diagnostic or contribute to diagnosis for specificdisorders. An aptamer isolated according the approach described hereincan be used to detect an amino acid in a sample, thereby providing orcontributing to a diagnosis for the associated disease or disorder.

For example, an aptamer described herein can be used as a diagnostic ofa congenital disease associated with the target molecule. As anotherexample, a tyrosine-specific aptamer can be used to diagnose tyrosinemiain a subject. As another example, an aptamer specific for the amino acidcitrulline can be used to diagnose or aid in the assessment of smallintestinal function (e.g., transplant recipients, includinggraft-vs-host disease). As another example, an aptamer specific for thecarbohydrate galactose can be used to diagnose or aid in the diagnosisof several forms of galactosemia.

Furthermore, an aptamer developed as described herein can be used tomonitor an amino acid associated with a disease or disorder and tomeasure compliance. For example, several amino acid disorders are knownto be treated by specific diets and aptamers described herein canprovide a tools allowing a subject or caregiver to monitor the efficacyof a specific diet. As another example, aptamers specific for valine,leucine, or isoleucine (branched chain amino acids) can be used forevaluation of nutritional status (e.g., dietary supplement used byathletes).

Several inborn errors of amino acid metabolism can be treated by specialdiets that either restrict protein intake (e.g., urea cycle defects,phenylketonuria, tryosinemia, glycine cleavage deficiency and others) orsupplement amino acids (e.g., 3-phosphoglycerate dehydrogenasedeficiency, MELAS syndrome and others). Conventional treatment involvesweekly or monthly determination of amino acid profiles and there are nomethods or tools that allow monitoring individual amino acids on a dailybasis (cf. glucose profiles in diabetes). Aptamers described herein andsensitive to the amino acid associated with such inborn errors of aminoacid metabolism can be used to monitoring individual amino acids on anhourly, daily, weekly, monthly, or yearly basis. Exemplary inborn errorsof amino acid metabolism are provided in the TABLE 1.

Change to Small Molecule Disease Indicative of DiagnosisPhenylketonuria, (several types) Phenylalanine, tyrosine Tyrosinemia -(several types, newborn Tyrosine, succinylacetone, immaturity and inbornerrors methionine Hawksinuria Glycine cleavage system deficiency Glycine3-Phosphoglycerat dehydrogenase deficiency Glycine ProprionicacidemiaGlycine Methylmalonicacidemia Glycine/methionine Histidinemia HistidineMSUD (Maple syrup urine disease) several Leucine, valine, isoleucineforms alloisoleucine, Isovaleric academia Leucine, glycineHomocystinuria (Cystathionine beta-synthase Homocysteine, methioninedeficiency, folate and B12 metabolism) Urea cycle defects (severaltypes) Citrulline, arginine, Argininosuccinate, Orotic acid, AmmoniaCitrullinemia type 2 (citrindefiency) Citrulline, galactose

A method based on aptamers developed as described herein can improvecurrent diagnostic approaches in clinically relevant conditions, extenddiagnostic capacity to low-prevalence conditions that remain undiagnoseddue to economic and technical reasons, uncover yet unrecognizedalterations in metabolism, or be used in monitoring the general healthof populations. Such methods can be effective when a health issue ischaracterized through a truly gross shift in patterns of metabolitefamilies, typical for serious metabolic problems, such as metabolicdisorders due to genetic polymorphisms (inborn errors). Gross shifts ofdominant components in the range of micro-to-millimolar concentrationscan be well suited for analysis as described herein, includingurinalysis for metabolic errors. Furthermore, analysis described herein(e.g., via arrays) can be useful in other biological fluids, such asserum, saliva, amniotic fluid, and CSF.

Over 98% of newborns in the US participate in a comprehensive programfor mass screening for inborn errors of metabolism on blood spots; thisprocess, made relatively fast and inexpensive by tandem massspectroscopy coupled with computer analysis, covers 30+ inborn errors ofmetabolism, treatable if caught at early stages, and 20+ untreatableconditions. While newborn screening is an undeniable success indeveloped countries, serious problems remain. For example, the rate offalse positives can be as high as 1.3%, with the positive predictivevalue of the test ranging from 3% (meaning 97% of positives are false)to 50%, depending on individual states (overall leading to estimated200,000 false positives each year in the US).

Approaches described herein can diagnose or monitor inborn errors thatinterfere with metabolic processes involving amino acids. If identifiedearly, the most serious consequences of these errors, such as mentalretardation, can be prevented, e.g., by careful changes in diet and byproviding supplements/drugs. The National Academy of ClinicalBiochemistry stresses in its “Practice Guidelines to Follow-up Testingfor Metabolic Diseases Identified in Newborn Screening” that acomprehensive amino-acid analysis provides relevant and timelycontribution to the differential diagnosis, with most tests for aminoacids performed in serum. The current analytical standard for amino acidanalysis in urine is post-derivatization cation exchange chromatographywith photometric detection of ninhydrin adducts; iTRAQ®-LC-MS/MS, andpost-derivatization GC-MS are being studied as alternatives.

In some embodiments, diagnostic methods disclosed herein may not fullyeliminate the need for chromatography and other diagnostic steps (e.g.,genetic). But such diagnostic methods can give a rapid single-stepoption for sorting out cases identified initially as low-to-moderaterisk; thus, as a fast second-tier confirmatory test, it can allow earlyfocus on correct diagnosis, and, if false positive is established, itcan provide important relief to a subject.

In post-prandial periods in patients with metabolic disorders thatinterfere with utilization of amino acids, there can be a transientstrong elevation above the renal reabsorption threshold of relevantmetabolites in plasma. This can result in spillage into urine, useful toconfirm the initial diagnosis or result in analysis of acidic componentsin urine as part of a differential diagnosis. To preserve homeostasis,unnecessary or toxic compounds are rapidly excreted, thus, increases inurine can be more dramatic than in blood.

In metabolic errors, the shifts in patterns of amino acids can be grossfor screened diseases. For example, it is known that in primaryaminoacidopathies: (i) in tyrosinemia type 1, changes in concentrationsof tyrosine in urine were >20-fold (2000 μmol/g creatinine); branchedchain amino acids change only minimally; (ii) in homocystinuria (e.g.,cystathionine beta synthase deficiency), it is known that homocystinebecomes detectable in urine (from ˜0 to about 100 μmol/g creatinine);(iii) in urea cycle disorders, e.g., citrullinemia (ASD) andargininosuccinicaciduria (ALD) (of interest for late onset as well), itis known that citrulline in urine increases more than 50-fold from <200to >10,000 μmol/g creatinine) and argininosuccinicate from ND to >1000μmol/g creatinine; (iv) in MSUD at day 3, it is known that leucine (alsoother branched-chain amino acids) increases >10-fold in serum (e.g.,from <200 to −2000 μM) with expected spillage into urine; any detectionof allo-isoleucine in either urine or serum (ND to av. 200 μM) is knownto be indicative of the diagnosis. In each of these cases, an aptamercan be developed, as described herein, to be sensitive to a metaboliteabove and thus contribute to diagnosis of the associated disease ordisorder.

Provided below is a list of specific diseases and conditions associatedwith a disruption of levels of an amino acid. Methods described hereinfor isolating an aptamer specific for an amino acid can be directedtowards an amino acid known to be diagnostic or contribute to diagnosisfor a specific disease or disorder appearing in the table below. Anaptamer isolated according the approach described herein can be used todetect an amino acid in a sample, thereby providing or contributing to adiagnosis for the associated disease or disorder appearing in TABLE 2.

TABLE 2 Pathological values/differential diagnosis of inborn errorsAmino acid Source Value Value Disorder(s) All amino acids U ↑ H Classicgalactosemia All amino acids U ↑ H Fanconi syndrome All amino acids U ↑H Fumarylacetoacetase deficiency (Tyrosinemia I) All amino acids U ↑ HGlutamylcysteine synthetase deficiency All amino acids U ↑ H Hereditaryfructose intolerance All amino acids U ↑ H Lowe syndrome All amino acidsU ↑ H Vitamin D-dependent rickets Neutral amino acids U ↑ H Hartnupdisorder Alanine B ↑ H Hyperammonemic syndromes Alanine B ↑ HMitochondrial disorders Alanine B ↑ H Pyruvate/lactate disordersβ-alanine B, U ↑ H β-Alaninemia β-alanine CSF ↑ H GABA-transaminasedeficiency β-alanine U ↑ H Methylmalonate semialdehyde dehydrogenasedeficiency β-alanine U ↑ H Pyrimidine disorders Allo-isoleucine B, U ↑ HE₃ Lipoamide dehydrogenase deficiency Allo-isoleucine U ↑ H Ethylmalonicaciduria Allo-isoleucine B, U ↑ H Maple syrup urine diseaseα-aminoadipic acid U ↑ H α-Aminoadipic/α-ketoadipic aciduriaα-aminoadipic acid U ↑ H Kearns-Sayre syndrome β-aminoisobutyric U ↑ Hβ-Alaninemia acid β-aminoisobutyric U ↑ H β-Aminoisobutyric acidaminotransferase deficiency acid (benign genetic marker)δ-Aminolevulinic acid U ↑ H Hereditary tyrosinemia I Argnine B ↓ LCreatine deficiency Arginine U ↑ H Cystinuria Arginine U ↑ H Dibasicaminoaciduria Arginine B ↓ L HHH syndrome Arginine B ↑ HHyperargininemia Arginine U ↑ H Lysinuric protein intolerance Arginine B↓ L Ornithine aminotransferase deficiency (gyrate atrophy)Argininosuccinate B, U, AF ↑ H Argininosuccinic aciduria(argininosuccinate lyase deficiency) Aspartic acid U ↑ H Dicarboxylicaminoaciduria Aspartylglucosamine B, U ↑ H Aspartylglucosamidasedeficiency Carnosine U ↑ H Carnosinemia Citrulline B ↑ HArgininosuccinic aciduria (argininosuccinate lyase deficiency)Citrulline B ↑ H Citrullinemia Citrulline B ↓ Lδ-Pyrroline-5-carboxylate synthase deficiency Citrulline B ↓ L Lysinuricprotein intolerance Citrulline B ↓ L NAGS, CPS, OTC deficienciesCitrulline B ↑ H Pyruvate carboxylase deficiency type B Citrulline B ↓ LRespiratory chain disorders Citrulline B, U ↑ H SaccharopinuriaCystathionine B, U ↑ H Cobalamin disorder Cystathionine B, U ↑ HCystathionase deficiency Cystathionine B, U ↑ H Cystathionine β-synthasedeficiency Cystathionine B, U ↑ H Methylene tetrahydrofolate reductasedeficiency Cystine U ↑ H Cystinuria Cystine U ↑ H Hyperlysinemia CystineU ↑ H Hyperornithinemia Cystine U ↑ H Lysinuric protein intoleranceCystine B ↓ L Molybdenum cofactor deficiency Cystine B ↓ L Sulfiteoxidase deficiency Ethanolamine U ↑ H Ethanolaminosis FormiminoglutamicU ↑ H Formiminoglutamic aciduria acid GABA B, U ↑ H β-Alaninemia GABACSF, B, U ↑ H GABA transaminase deficiency Glutamic acid U ↑ HDicarboxylic aminoaciduria Glutamic acid P ↑ H Glutamic acidemiaGlutamine CSF ↑ H Adenosine deaminase deficiency Glutamine B, U ↑ H CPS& OTC deficiencies Glutamine B, U, CSF ↑ H Hyperammonemic syndromesGlutamine B ↓ L Maple syrup urine disease Glutathionine U ↑ H γ-Glutamyltranspeptidase deficiency Glycine U, B, CSF ↑ H Cobalamin disordersGlycine U, B, CSF ↑ H D-Gyceric aciduria Glycine U ↑ H Familial renaliminoglycinuria Glycine U ↑ H Hyperprolinemia I & II Glycine U, B, CSF ↑H Methylmalonic acidemia Glycine U, B, CSF ↑ H Nonketotichyperglycinemia Glycine U, B, CSF ↑ H Propionic acidemia Glycine B, CSF↓ L Serine deficiency disorders Glycylproline U ↑ H Prolidase deficiencyHawkinsin U ↑ H Hawkinsinuria Histidine B, U ↑ H HistidinemiaHomoarginine B, U ↑ H Hyperlysinemia Homocarnosine CSF ↑ HHomocarnosinosis Homocitrulline U ↑ H HHH syndrome Homocitrulline B, U ↑H Saccharopinuria Homocyst(e)ine U ↑ H Adenosine deaminase deficiencyHomocyst(e)ine B, U ↑ H Cobalamin disorders Homocyst(e)ine B, U ↑ HCystathionine β-synthase deficiency Homocyst(e)ine B, U ↑ H Folatedisorders Homocyst(e)ine B ↑ H Methionine adenosyltransferase deficiencyHomocyst(e)ine B ↑ H Nonketotic hyperglycinemia Homocysteine-cysteine B↑ H Cystathionine β-synthase deficiency disulfide Homocysteine-cysteineU ↑ H Cystinuria disulfide Homocysteine-cysteine B ↑ HHyperhomocysteinemia disulfide Hydroxylysine U ↑ H HydroxylysinuriaHydroxyproline U ↑ H Familial renal iminoglycinuria Hydroxyproline U ↑ HHydroxyprolinuria Hydroxyproline U ↑ H Hyperprolinemia I & IIImidodipeptides U ↑ H Prolidase deficiency Isoleucine B, U ↑ H E₃Lipoamide dehydrogenase deficiency Isoleucine B, U ↑ H Maple syrup urinedisease Leucine B, U ↑ H E₃ Lipoamide dehydrogenase deficiency LeucineB, U ↑ H Maple syrup urine disease Lysine B ↓ L Creatine deficiencyLysine U ↑ H Cystinuria Lysine U ↑ H Dibasic aminoaciduria Lysine B ↓ LHHH syndrome Lysine B, U ↑ H Hyperlysinemia Lysine U ↑ H Lysinuricprotein intolerance Lysine B ↓ L Ornithine aminotransferase deficiency(gyrate atrophy) Lysine B ↑ H Pyruvate carboxylase deficiency type BLysine B, U ↑ H Saccharopinuria β-Mercaptolactate- U ↑ Hβ-mercaptolactate-cysteine disulfiduria cysteine disulfide Methionine P,CSF ↑ H Adenosine deaminase deficiency Methionine B ↓ L Cobalamindisorders Methionine B, U ↑ H Cystathionine β-synthase deficiencyMethionine B ↑ H Hypermethioninemias Methionine CSF ↓ LMethylenetetrahydrofolate reductase deficiency Methionine sulfoxide B ↑H Cystathionine β-synthase deficiency Methionine sulfoxide B ↑ HHypermethioninemias Ornithine B ↑ H Creatine deficiency Ornithine U ↑ HCystinuria Ornithine B ↓ L Δ-Pyrroline-5-carboxylate synthase deficiencyOrnithine U ↑ H Dibasic aminoaciduria Ornithine B ↑ H HHH syndromeOrnithine U ↑ H Hyperlysinemia Ornithine U ↑ H Lysinuric proteinintolerance Ornithine B ↑ H Ornithine aminotransferase deficiency(gyrate atrophy) Phenylalanine B ↑ H Hereditary tyrosinemia IPhenylalanine B, U ↑ H Hyperphenyalaninemia Phenylalanine B ↑ H Neonataltransient tyrusinemia Phenylalanine B, U ↑ H PKU Phenylalanine B, U ↑ HPterin disorders Phosphoethanolamine U ↑ H Hypophosphatasia (rickets)o-Phosphohydroxylysine U ↑ H o-Phosphohydroxylysinuria Pipecolic acid B↑ H Hyperlysinemia Pipecolic acid U ↑ H Hyperprolinemia II Pipecolicacid B, U ↑ H Peroxisomal disorders Proline B ↓ LΔ-Pyrroline-5-carboxylate synthase deficiency Proline U ↑ H Familialrenal iminoglycinuria Proline B, U ↑ H Hyperprolinemia I & II Proline B↑ H Pyruvate carboxylase deficiency type B Saccharopine B, U ↑ HSaccharopinuria Sarcosine B, U ↑ H Glutaric acidemia II Sarcosine B, U ↑H Mitochondrial disorders Sarcosine B, U ↑ H Sarcosinemia Serine B ↓ LCystathionine β-synthase deficiency Serine B, CSF ↓ L Serine deficiencydisorders S-Sulfocysteine B, U ↑ H Molybdenum cofactor deficiencyS-Sulfocysteine B, U ↑ H Sulfite oxidase deficiency Taurine U ↑ Hβ-Alaninemia Taurine U ↑ H Molybdenum cofactor deficiency Taurine U ↑ HSulfite oxidase deficiency Tryptophan U ↑ H Tryptophanuria Tyrosine B, U↑ H 4-Hydroxyphenylpyruvate dioxygenase deficiency (Tyrosinemia III)Tyrosine B, U ↑ H 4-Hydroxyphenylpyruvate oxidase deficiency Tyrosine B,U ↑ H Fumarylacctoaectase deficiency (Tyrosinemia I) Tyrosine B, U ↑ HNeonatal transient tyrosinemia Tyrosine B ↓ L PKU Tyrosine B ↓ L Pterindisorders Tyrosine B, U ↑ H Tyrosine aminotransferase deficiency(Tyrosinemia II) Valine B, U ↑ H E3 Lipoamide dehydrogenase deficiencyValine B, U ↑ H Hypervalinemia Valine B, U ↑ H Maple syrup urine diseaseB, blood; U, urine; CSF, cerebrospinal fluid; H, high; L, low.

Diagnostic methods discussed above can be useful for urine samples.Urine is presently understood to be a complex matrix for analysis,dependent on kidney filtration and reabsorption efficacy, oftenrequiring collection of 24-hour urines, often under professionalsupervision in metabolic wards. Aside from standardization againstcreatinine, many analytes require deconjugation procedures,derivatizations, extraction, or solid state isolation steps. Methodsdescribed herein can replace traditionally challenging procedures,typically used for confirmatory second-tier assays, with simple andrapid protocols suitable for routine use “next-to-subject”.

In the context of newborn screening, urinalysis has been validated basedon post-derivatization GC-MS with standard additions for more than 130different inborn metabolic inflictions (see Matsumoto 1996 MassSpectrometry Reviews 15, 43-57). Methods described herein can avoid themore laborious and complicated GC-MS analysis. Such a break through isprovided by aptameric sensors, with their ability to transduce adaptivebinding into a signal, described herein.

In healthy urine, sets of two specific or optimized differentiallyresponsive aptameric sensors can have very similar ratios of responses;in urines with gross shifts, these ratios can change dramatically,regardless of renal filtration. For example, aside from the detection ofallo-isoleucine, the diagnosis of MSUD is conventionally made based onthe ratio of leucine and isoleucine to phenylalanine in chromatographsof derivatives. According to compositions and methods described herein,the same effect can be achieved in a single-step measurement.

Molecular Biology

Design, generation, and testing of the variant nucleotides having theabove required percent identities and retaining a required aptamericactivity is within the skill of the art. For example, directed evolutionand rapid isolation of mutants can be according to methods described inreferences including, but not limited to, Link et al. (2007) NatureReviews 5(9), 680-688; Sanger et al. (1991) Gene 97(1), 119-123;Ghadessy et al. (2001) Proc Natl Acad Sci USA 98(8) 4552-4557. Thus, oneskilled in the art could generate a large number of nucleotide variantshaving, for example, at least 90-99% identity (e.g., 95%) to a referencesequence described herein and screen such for desired phenotypesaccording to methods routine in the art.

Nucleotide and/or amino acid sequence identity percent (%) is understoodas the percentage of nucleotide or amino acid residues that areidentical with nucleotide or amino acid residues in a candidate sequencein comparison to a reference sequence when the two sequences arealigned. To determine percent identity, sequences are aligned and ifnecessary, gaps are introduced to achieve the maximum percent sequenceidentity. Sequence alignment procedures to determine percent identityare well known to those of skill in the art. Often publicly availablecomputer software such as BLAST, BLAST2, ALIGN2 or Megalign (DNASTAR)software is used to align sequences. Those skilled in the art candetermine appropriate parameters for measuring alignment, including anyalgorithms needed to achieve maximal alignment over the full-length ofthe sequences being compared. When sequences are aligned, the percentsequence identity of a given sequence A to, with, or against a givensequence B (which can alternatively be phrased as a given sequence Athat has or comprises a certain percent sequence identity to, with, oragainst a given sequence B) can be calculated as: percent sequenceidentity=X/Y100, where X is the number of residues scored as identicalmatches by the sequence alignment program's or algorithm's alignment ofA and B and Y is the total number of residues in B. If the length ofsequence A is not equal to the length of sequence B, the percentsequence identity of A to B will not equal the percent sequence identityof B to A.

Generally, conservative substitutions can be made at any position solong as the required activity is retained. Deletion is the replacementof a nucleic acid by a direct bond. Positions for deletions include thetermini and linkage positions. Insertions are introductions of nucleicacids into the chain, a direct bond formally being replaced by one ormore nucleic acids. Nucleic acid sequence can be modulated with the helpof art-known computer simulation programs.

Kits

Also provided are kits. Such kits can include an agent or compositiondescribed herein and, in certain embodiments, instructions foradministration. Such kits can facilitate performance of the methodsdescribed herein. When supplied as a kit, the different components ofthe composition can be packaged in separate containers and admixedimmediately before use. Components include, but are not limited totarget molecule, derivatization agent, aptamer, or materials or reagentsfor identification or isolation of an aptamer. Such packaging of thecomponents separately can, if desired, be presented in a pack ordispenser device which may contain one or more unit dosage formscontaining the composition. The pack may, for example, comprise metal orplastic foil such as a blister pack. Such packaging of the componentsseparately can also, in certain instances, permit long-term storagewithout losing activity of the components.

Kits may also include reagents in separate containers such as, forexample, sterile water or saline to be added to a lyophilized activecomponent packaged separately. For example, sealed glass ampules maycontain a lyophilized component and in a separate ampule, sterile water,sterile saline or sterile each of which has been packaged under aneutral non-reacting gas, such as nitrogen. Ampules may consist of anysuitable material, such as glass, organic polymers, such aspolycarbonate, polystyrene, ceramic, metal or any other materialtypically employed to hold reagents. Other examples of suitablecontainers include bottles that may be fabricated from similarsubstances as ampules, and envelopes that may consist of foil-linedinteriors, such as aluminum or an alloy. Other containers include testtubes, vials, flasks, bottles, syringes, and the like. Containers mayhave a sterile access port, such as a bottle having a stopper that canbe pierced by a hypodermic injection needle. Other containers may havetwo compartments that are separated by a readily removable membrane thatupon removal permits the components to mix. Removable membranes may beglass, plastic, rubber, and the like.

In certain embodiments, kits can be supplied with instructionalmaterials. Instructions may be printed on paper or other substrate,and/or may be supplied as an electronic-readable medium, such as afloppy disc, mini-CD-ROM, CD-ROM, DVD-ROM, Zip disc, videotape, audiotape, and the like. Detailed instructions may not be physicallyassociated with the kit; instead, a user may be directed to an Internetweb site specified by the manufacturer or distributor of the kit.

Compositions and methods described herein utilizing molecular biologyprotocols can be according to a variety of standard techniques known tothe art (see, e.g., Sambrook and Russel (2006) Condensed Protocols fromMolecular Cloning: A Laboratory Manual, Cold Spring Harbor LaboratoryPress, ISBN-10: 0879697717; Ausubel et al. (2002) Short Protocols inMolecular Biology, 5th ed., Current Protocols, ISBN-10: 0471250929;Sambrook and Russel (2001) Molecular Cloning: A Laboratory Manual, 3ded., Cold Spring Harbor Laboratory Press, ISBN-10: 0879695773; Elhai, J.and Wolk, C. P. 1988. Methods in Enzymology 167, 747-754; Studier (2005)Protein Expr Purif. 41(1), 207-234; Gellissen, ed. (2005) Production ofRecombinant Proteins: Novel Microbial and Eukaryotic Expression Systems,Wiley-VCH, ISBN-10: 3527310363; Baneyx (2004) Protein ExpressionTechnologies, Taylor & Francis, ISBN-10: 0954523253).

Definitions and methods described herein are provided to better definethe present disclosure and to guide those of ordinary skill in the artin the practice of the present disclosure. Unless otherwise noted, termsare to be understood according to conventional usage by those ofordinary skill in the relevant art.

In some embodiments, numbers expressing quantities of ingredients,properties such as molecular weight, reaction conditions, and so forth,used to describe and claim certain embodiments of the present disclosureare to be understood as being modified in some instances by the term“about.” In some embodiments, the term “about” is used to indicate thata value includes the standard deviation of the mean for the device ormethod being employed to determine the value. In some embodiments, thenumerical parameters set forth in the written description and attachedclaims are approximations that can vary depending upon the desiredproperties sought to be obtained by a particular embodiment. In someembodiments, the numerical parameters should be construed in light ofthe number of reported significant digits and by applying ordinaryrounding techniques. Notwithstanding that the numerical ranges andparameters setting forth the broad scope of some embodiments of thepresent disclosure are approximations, the numerical values set forth inthe specific examples are reported as precisely as practicable. Thenumerical values presented in some embodiments of the present disclosuremay contain certain errors necessarily resulting from the standarddeviation found in their respective testing measurements. The recitationof ranges of values herein serves as a shorthand method of referringindividually to each separate value falling within the range. Unlessotherwise indicated herein, each individual value is incorporated intothe specification as if it were individually recited herein. Similarly,it is understood that recitation of ranges of values herein serves as ashorthand method of referring to ranges between each of the recitedvalues.

In some embodiments, the terms “a” and “an” and “the” and similarreferences used in the context of describing a particular embodiment(especially in the context of certain of the following claims) can beconstrued to cover both the singular and the plural, unless specificallynoted otherwise. In some embodiments, the term “or” as used herein,including the claims, is used to mean “and/or” unless explicitlyindicated to refer to alternatives only or the alternatives are mutuallyexclusive.

The terms “comprise,” “have” and “include” are open-ended linking verbs.Any forms or tenses of one or more of these verbs, such as “comprises,”“comprising,” “has,” “having,” “includes” and “including,” are alsoopen-ended. For example, any method that “comprises,” “has” or“includes” one or more steps is not limited to possessing only those oneor more steps and can also cover other unlisted steps. Similarly, anycomposition or device that “comprises,” “has” or “includes” one or morefeatures is not limited to possessing only those one or more featuresand can cover other unlisted features.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.“such as”) provided with respect to certain embodiments herein isintended merely to better illuminate the present disclosure and does notpose a limitation on the scope of the present disclosure otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element essential to the practice of thepresent disclosure.

Groupings of alternative elements or embodiments of the presentdisclosure disclosed herein are not to be construed as limitations. Eachgroup member can be referred to and claimed individually or in anycombination with other members of the group or other elements foundherein. One or more members of a group can be included in, or deletedfrom, a group for reasons of convenience or patentability. When any suchinclusion or deletion occurs, the specification is herein deemed tocontain the group as modified thus fulfilling the written description ofall Markush groups used in the appended claims.

Citation of a reference herein shall not be construed as an admissionthat such is prior art to the present disclosure.

Having described the present disclosure in detail, it will be apparentthat modifications, variations, and equivalent embodiments are possiblewithout departing the scope of the present disclosure defined in theappended claims. Furthermore, it should be appreciated that all examplesin the present disclosure are provided as non-limiting examples.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present disclosure. It should be appreciated by those of skill inthe art that the techniques disclosed in the examples that followrepresent approaches the inventors have found function well in thepractice of the present disclosure, and thus can be considered toconstitute examples of modes for its practice. However, those of skillin the art should, in light of the present disclosure, appreciate thatmany changes can be made in the specific embodiments that are disclosedand still obtain a like or similar result without departing from thespirit and scope of the present disclosure.

Example 1 Selection Principles

The following example describes the selection protocol. A solution-phaseprotocol was used as the starting point for selection to identifyaptameric sensors for steroids suitable for cross-reactive arrays[12-14]. A receptor*target complex is used to selectively interact withthe aptamer (see e.g., FIG. 1B).

A capture oligonucleotide, complementary to the part of the primer of alibrary of random oligonucleotides is displayed within the affinitymatrix in a chromatography column. A capture oligonucleotide is shown inFIG. 1B, where C is attached to streptavidin column via biotin—B—at 3′end. A library of random oligonucleotides is shown in FIG. 1B, whereN(m) represents a random region of m bases, with m being any numberbetween 1 and 100. Bases shown in FIG. 1B are primer regions used forPCR.

The capture strand is used to immobilize the library members andsolution-phase target(s) is applied during the affinity elution step.Aptameric structures within this library that interact with targetmolecule(s) in a way that promotes the formation of a stem competingwith the capture oligonucleotide (i.e., displacing the captureoligonucleotide) will be preferably eluted from the column and, thus,favored during the selection process. The method is very convenient asit directly yields aptamers in an easy-to-test sensor form at the end ofthe selection[15,16].

Here, synthetic receptors are added to the affinity elution step in thepresence of an excess of target molecule itself, to push the equilibriumtowards the formation of complex between receptor and target, while alsocounter-selecting against target and receptor individually. Thisprocedure results in favoring the elution of aptamers that interact(form the stem) selectively with the complex (see e.g., FIG. 1A-B).

Example 2 Aptameric Sensor with Tyrosine as Target

The following example describes the high-affinity and high-specificity,low complexity aptameric sensors, targeting tyrosine.

The first target was chosen based on the desire to compare results of astandard SELEX protocol without addition of any receptor, for a targetthat can be representative of a “typical” small organic molecule. Theamino acid, tyrosine, was selected based on characteristics such aselectron rich aromatic group, only one positive charge, and a mediocreability to form highly organized hydrogen bonding networks. Thesecharacteristics can be representative of typical targets (e.g.,dopamine, cocaine) that are expected to bind to aptamers in a low-to-midmicromolar range, as it is indeed the case with a reported 63-merreceptor with K_(d)˜35 μM [17]. Tyrosine (see e.g., FIG. 3A) can also bean interesting target from the clinical chemistry perspective. Increasein tyrosine levels can indicate inborn metabolic errors (e.g., differenttypes of tyrosinemia).

Cp*Rh(III) was selected as a synthetic receptor for tyrosine (see e.g.,FIG. 2, ref. [18] in the context of cross-reactive arrays forclassification of amino acids, peptides, and amino sugars). This complexwould add to the existing functionalities within tyrosine: a metal-ioncoordination site, an additional hydrophobic surface, and wouldeliminate several rotational freedoms present in free tyrosine as wellas the negative charge of carboxylate. A parallel selection wasperformed, as a control, without the addition of Cp*Rh(III). N(30)library was used to ensure full coverage of receptor space in bothselections. Because the complex should not be selective for amino acids,the selectivity should originate from the aptamer.

Further, as other amino acids would compete for binding, in a typicalapplication an excess of complex would convert all amino acids in highlydiluted bodily fluids into complexes, with the aptamer picking up onlyone of them.

During selection, the Cp*Rh(III) was added at a concentration of 50 pMat the affinity elution step in the presence of 1 mM tyrosine. Theseconditions ensured that the receptor was over 90% in the complex basedon an estimated association constants of amino acids with the receptor.Counter-selection was performed by adding the receptor in the absence oftyrosine to the elution buffer. These conditions reduced opportunitiesfor favoring aptamers in selection that would bind to the receptor inthe absence of target.

Intermittent counter selections with tyrosine were also introduced tomaximize binding to complex itself. After eleven rounds of selection,the cloned pool was analyzed and significant convergence was observed,with

Cp*Rh(III)*Tyr binding motif (see e.g., FIG. 3B). The selection directlyled to an aptamer in the form that was suitable for a competitive assaywith oligonucleotide (see e.g., FIG. 3C). The sensor showednear-absolute selectivity for the complex over its individual componentsand over tested examples of natural amino acids, but for the smallresponse to phenylalanine (see e.g., FIG. 3E). The half-saturation pointin the selection buffer for a sensor in a competitive assay was between250-300 nM, which allowed the determination of calculated K_(d) for thecomplex of 22-25 nM. This value is approximately an order of magnitudehigher than the tightest binding aptamer against any amino acid (cf.,arginine) [19]. In parallel, SELEX was performed in the absence of areceptor, but under otherwise identical conditions and no sensorscapable of sensing tyrosine were isolated according to this conventionalapproach.

Because Cp*Rh(III) is a non-specific receptor, other amino acids andpotential ligands could compete in mixtures. But the high affinity of asensor can enable detection of small changes of concentration of targetin complex mixtures at high dilutions (500-1000).

To demonstrate this principle, tyrosine was added to healthy sera atconcentrations that would be characteristic for tyrosinemia. Upondilution of serum 1:100-200 in detection buffer, the sensor was clearlyable to distinguish spiked from non-spiked samples. Similar results wereobtained with urine.

The approach as described herein specifically targets the complexes ofsynthetic receptors and their ligands rather than individual componentsof the complex, rendering the approach different from more traditionalincorporation of modified bases or cofactors into aptamers. Thisapproach can provide for detection of small concentrations of aminoacids in the presence of an excess of ligand (e.g., a highly dilutedsample of a biological fluid containing an amino acid).

Human serum, which contains numerous compounds forming complexes with areceptor, was obtained and serial diluted (before and after spiking itwith 1 mM tyrosine). The samples mimic dilutions of healthy serum andserum characteristic of tyrosinemia. The two at dilutions of 1:80 and1:160 were clearly distinguishable (see e.g., FIG. 3F). The dataindicates that an increase in tyrosine concentration characteristic fora disease at 1:100 dilution can be detected in the presence of an excessCp*Rh(III), without any derivatization and in the presence of numerousagents that would otherwise interfere.

The protocols described in this example can also be used for an array ofaptamers to read compositions of amino acids in highly diluted urinesamples. The assay, as described herein is the first of its kind inclinical chemistry that target complexes with high-specificity.

In situ derivatization, with completely non-specific organometallicreceptors, such as Cp*Rh(III), can be used in selection of aptamers toshift their selectivity and sensitivity into practically useful ranges,by a combination of a solution-phase SELEX and counter selection againstindividual components. More specifically, based on demonstrations withtyrosine, a long standing problem has been solved: detection of a changein an amino acid concentration in serum (or other bodily fluids) with asimple dilute-and-measure assay.

Example 3 Aptameric Sensor with Arginine as Target

The following example describes high-affinity and high-specificity, lowcomplexity aptameric sensors targeting arginine using the procedure asdescribed in Examples 1-2. Arginine was the target molecule, Cp*Rh wasused as the receptor, and the sensor was based on AKArg-1. The sensorwas highly selective over other amino acids including similar citrulline(see e.g., FIG. 4).

In situ derivatization, with completely non-specific organometallicreceptors, such as Cp*Rh(III), can be used in selection of aptamers toshift their selectivity and sensitivity into practically useful ranges,by a combination of a solution-phase SELEX and counter selection againstindividual components. More specifically, based on demonstrations witharginine, a long standing problem has been solved: detection of a changein an amino acid concentration in serum (or other bodily fluids) with asimple dilute-and-measure assay.

Example 4 Aptameric Sensor with Glucose as Target

The following example describes the high-affinity and high-specificity,low complexity aptameric sensors, targeting glucose.

Numerous attempts to isolate glucose binding aptamers resulted inmultiple candidate receptors that were somewhat responsive tofluorophore derivatized receptors at higher millimolar concentrations(>50 mM), but were difficult to reproduce. The control experiments, inwhich fluorescein would be attached to a double helical structure,yielded similar magnitudes of responses, leading to the conclusion thatthe aptamers isolated, even if real, would not have been suitableanalytical and nanotechnology applications.

Interactions between boronic acids and diols can be used as a basis forconstruction of glucose-responsive sensors. Here, a glucose-selectivebis-boronic receptor (see e.g., FIG. 5A), with K_(d) for glucose of ˜500μM, was chosen. The bis-boronic receptor can be selective for glucoseover other sugars. The bis-boronic receptor can operate at physiologicalconditions. The transduction of a binding event of the Shinkai'sreceptor to glucose into a fluorescent signal, should provide animportant internal control for any isolated aptamer. It is expected thatfluorescence indicating the formation of a complex should match anychanges in aptameric sensor response.

The Shinkai's receptor was synthesized from a bis-aldehyde. Duringselection, the receptor was added at concentrations of 50 μM at theaffinity elution step in the presence of 40 mM glucose; these conditionsensured that the receptor was over 90% in the complex. Counter-selectionwas performed by adding the receptor in the absence of glucose to theelution buffer. Counter-selection for glucose was not performedseparately because the response of aptamers to glucose would have beenconsidered beneficial on its own. Through these conditions,opportunities for favoring aptamers in selection that would bind to thereceptor in the absence of glucose were minimized (see FIG. 5D; FIG.5E). As a result, after 13 cycles a series of aptamers were isolated,that, when turned into sensors (see e.g., FIG. 5B, FIG. 5C) behaved aspredicted and responded to an increase in glucose concentrations.

A predominant aptameric glucose sensor in shown in FIG. 5B, based onYKG-1. The response of this sensor at 520 nm to the addition of glucosein the presence of receptor correlated with the response of receptorbinding to glucose at 427 nm (see FIG. 5F). The selectivity for glucosewas improved. The symmetrical structure of the receptor, the unusualshape of a binding isotherm, and binding of more than one equivalent ofcomplex at saturating conditions in titration experiments of YKG-1support the binding of two boronic acid-glucose complexes to oneaptamer.

Sensors specific for glucose (see e.g., FIG. 5I, FIG. 5L), fructose (seee.g., FIG. 5J, FIG. 5M), and galactose (see e.g., FIG. 5K, FIG. 5N) werealso identified.

In situ derivatization with a receptor designed to have some degree ofspecificity, such as Shinkai's sensor, can be used in the selection ofaptamers to shift their selectivity and sensitivity into practicallyuseful ranges, by a combination of a solution-phase SELEX and counterselection against individual components.

Example 5 Aptameric Sensors with Unpaired Bases

The following example shows a series of aptamers having a nucleic acidsequence with one or more unpaired bases such that a metal complex canbind a pocket formed by the one or more unpaired bases and also bindsthe target amino acid. An exemplary binding site is formed by the G-Amismatch surrounded by binding base pairs (e.g., G-C, G-T, A-T, A-U oranalogs) as shown below (see FIG. 7A):

A series of aptamers were formed having an unbound nucleic acid pocket(see e.g., FIG. 7B-G). FIG. 7B-G shows a Cp*Rh(III)-amino acid bindingaptamer in sensor form along with the amino acid for which initialselection was performed (e.g., Tyr for FIG. 7B. Phe for FIG. 7C,Citrulline in FIG. 7D., Gln in FIG. 7E). In some aptamers, a motif wasrecognized straight from folding programs, such as in FIG. 7B-E. In someaptamers, a motif can be recognized from primary sequence (i.e., motifdoes not necessarily show in folding program, as in two Lys sensors),such as in FIG. 7F-G. In some aptamers, an unbound nucleic acid pocketbinds Cp*Rh (compare FIG. 7B-G), but can also bind other metals (compareCu2+ in FIG. 7H).

The following examples show a series of aptamers having at least twounpaired bases forming a pocket that binds a metal complex or an aminoacid target molecule.

An exemplary motif having a plurality of unpaired bases forming a pocketthat binds a metal complex or an amino acid target molecule is shown inFIG. 8A. Exemplary aptamers include an Arg selective aptamer (see e.g.,FIG. 8B); a Trp selective aptamer (see e.g., FIG. 8C); a Gly selectiveaptamer (see e.g., FIG. 9A); an Asn selective aptamer (see e.g., FIG.9C); and a Gly non-specific aptamer (see e.g., FIG. 9C).

The following examples shows an aptamer having multiple foldingconfigurations (compare FIG. 10A and FIG. 10B), which is selective forLeu over Ile and has a plurality of unpaired bases forming a pluralityof pockets, one of more of which pockets can bind a metal complex andalso an amino acid target molecule. A Cp*Rh(III) can bind more than onesite, such as additional G's that can be targeted.

Example 6 Use of Aptameric Sensors with Unpaired Bases

The following example shows an aptamer with unpaired bases that isreactive for Phe and cross-reactive for Trp, along with use thereof.

An aptamer a plurality of unpaired bases and reactive for Phe andcross-reactive for Trp is shown in FIG. 11A. This aptamer was used todetected Phe concentration (μM) as a function of time (hr) in serumsamples from capillary blood of a female subject (TWP) and a malesubject (MNS) that took 100 mg of phenylanine per kg body weight bymouth at time zero (see e.g., FIG. 11B). The phenylalanine concentrationin blood rises significantly at this dosage (see 1 hr in FIG. 11B).Every hour, blood was measured for the phenylalanine concentration. In ahealthy subject, the enzymes that break down phenylalanine (e.g.,phenylalanine hydroxylase (PAH) or BH4-cofactor, alone or together) arestimulated and break down phenylalanine resulting in decreasedconcentration (see 2-5 hr in FIG. 11B). In subjects with PKU this doesnot happen, as PKU is caused by mutations in the degrading enzymes.

An aptamer a plurality of unpaired bases and reactive for Phe is shownin FIG. 12A. This aptamer sensor mixture (not including Cp*Rh) wasincubated with concentrations of amino acids (Phe, Tyr, Trp, Gly) andfluorescence (RFU) measured (see e.g., FIG. 12B).

An aptamer a plurality of unpaired bases and reactive for Phe is shownin FIG. 12C. This aptamer sensor mixture (not including Cp*Rh) wasincubated with concentrations of amino acids (Phe, Trp, Tyr) andfluorescence (RFU) measured (see e.g., FIG. 12D).

SEQUENCE LISTING SEQ ID NO: 1 5′ primer end of library oligonucleotidesCTCTCGGGACGAC SEQ ID NO: 2 3′ primer end of library oligonucleotidesGTCGTCCC SEQ ID NO: 3 Aptamer against glucose-boronic acid complexShort binding form GACAGCCGAGTGCATTCAACAGCCGAGTC SEQ ID NO: 4Glucose-BA_01 CTCGGGACGACAGCCGAGTTCAGGGATTCCCTAACAGCCGAGTCGTCCCSEQ ID NO: 5 Glucose-BA_07CTCGGGACGACAGCCGAGTTATGACATTCAATAACAGCCGAGTCGTCCC SEQ ID NO: 6Glucose-BA_08 CTCGGGACGACCAGCCGAGATTTTGCATAAAAACAGCCGAGGTCGTCCCSEQ ID NO: 7 Glucose-BA_09CTCGGGACGACCAGCCGAGATAGGTCGTTCTATCAGCCGAGGTCGTCCC SEQ ID NO: 8Glucose-BA_10 CTCGGGACGACAACCGAGTAGGATACTAAGCATCCAGCGGAGTCGTCCCSEQ ID NO: 9 Glucose-BA_11CTCGGGACGACAGCCGAGGAAACAAACTTTTTTCCAGCCGAGTCGTCCC SEQ ID NO: 10Glucose-BA_12 CTCGGGACGACCGCGGGAGCAATGCGATGACGAAGGACGGGGTCGTCCCSEQ ID NO: 11 Glucose-BA_13CTCGGGACGACCGGAGCTCCTGCGATTGACTAAAAGGAAGGTCGTCCC SEQ ID NO: 12Glucose-BA_14 CTCGGGACGACAGCCGAGTCAAAGTTTAACTTGACAGCCGAGTCGTCCCSEQ ID NO: 13 Glucose-BA_15CTCGGGACGACGGGGAACGTTTTCGTGGATGAGCTGGCGACGTCGTCCC SEQ ID NO: 14Glucose-BA_16 CTCGGGACGACGGGGGAGAGTATTGGATGACCGCAGGGACCGTCGTCCCSEQ ID NO: 15 Glucose-BA_17CTCGGGACGACGGGGGGAACATTGTGATCTCGTTAGAGCACGTCGTCCC SEQ ID NO: 16 GLUBA02CTCTCGGGACGACGGACCGTTAGGGGAGCCAGTGCGCGATGACGTCGTCC C SEQ ID NO: 17GLUBA09 CTCTCGGGACGACAGCCGAGTTCAGGGAcTTCCCTAACAGCCGAGTCGTC CCSEQ ID NO: 18 GLUBA09_M1 CTCTCGGGACGACAGCCGAGTTGATTCAACAGCCGAGTCGTCCCSEQ ID NO: 19 GLUBA17 CTCTCGGGACGACAGCCGAGCACTACATTAGTTGGGCAGCCGAGTCGTCCC SEQ ID NO: 20 GLUBAN3W10CTCTCGGGACGACGACCGTAGGGGTAGCTGTATATGCGGATGAGTCGTCC C SEQ ID NO: 21GLUBAN3W11 CTCTCGGGACGACAGGGGGTAGGGGGCCCGGACTGTTAAGGGTGTCGTCC CSEQ ID NO: 22 GLUBAN3W19CTCTCGGGACGACGGGACCAACCGGGATGAGCATAAGTGCGACGTCGTCC C SEQ ID NO: 23FrucBA02 CTCTCGGGACGACGGCTGGCACGTTTGGTTCAAGAATGTGGGTGTCGTCC CSEQ ID NO: 24 FrucBA02_M1 CTCTCGGGACGACGGCTGGCACGTTGAATGTGGGTGTCGTCCCSEQ ID NO: 25 FrucBA05CTCTCGGGACGACGGACAGAGGTTCGAGCGTGCGCTCTAGGAAGTCGTCC C SEQ ID NO: 26GalacBA01 CTCTCGGGACGACCCAGGTGTCCTGCTTCTCAGTAGTAGGTTAGTCGTCC CSEQ ID NO: 27 GalacBA04CTCTCGGGACGACCACTACGCATAGTTTCTATCGCCAGGAAGGGTCGTCC C SEQ ID NO: 28GalacBA06 CTCTCGGGACGACCGAGTAGGTGTCCTGGATGCAGGTTTGGAGGTCGTCC CSEQ ID NO: 29 BAOnly01CTCTCGGGACGACCAGGTGGGGCTGCTCAAGTGGAGGTTCCTCGTCGTCC C SEQ ID NO: 30BAOnly03 CTCTCGGGACGACCAGAGGGGCCTCAAATGTGGGGTGTTGCTCGTCGTCC CSEQ ID NO: 31 Aptamer against Arginine-Cp*Rh complex Short binding formGACGACACGGGCGTCCCTTATCACAAGGAGAGTGAGTC SEQ ID NO: 32 Arginine-Cp*Rh_02CTCTCGGGACGACGGGTGTCCCTGTGGACCTGTACATAGGAGAGTCGTCC C SEQ ID NO: 33Arginine-Cp*Rh_03 CTCTCGGGACGACGCGGGTGTCCCTTGGTAAACCAAGGAGAGTGTCGTCC CSEQ ID NO: 34 Arginine-Cp*Rh_04CTCTCGGGACGACGGCTAGGAGAGGTGTCCGGGTGTCCCAGGTGTCGTCC C SEQ ID NO: 35Arginine-Cp*Rh_05 CTCTCGGGACGACCCACGAGAGACTCCAAACGATTGCCGTCCCSEQ ID NO: 36 ARG01_CpCTCTCGGGACGACGACACGGGCGTCCCTTCACAAGGAGAGTGAGTCGTCC C SEQ ID NO: 37AspaCp01 CTCTCGGGACGACGGCACTTGTTGCGTGAAGCGTATGCGAATAGTCGTCC CSEQ ID NO: 38 AspaCp03CTCTCGGGACGACGGGCCACGTTTTCCAGGTACTTTCTAAGGGGTCGTCC C SEQ ID NO: 39AspaCp04 CTCTCGGGACGACGGGCCTTCGGTGGCTGAGCATAGCGATGGGGTCGTCC CSEQ ID NO: 40 CIT30N02_Cp*RhCTCTCGGGACGACGGCGGGGAAACAGCTGCAAAATGTGGAGTAGTCGTCC C SEQ ID NO: 41GlutaCp02 CTCTCGGGACGACGGCGGGTGAATGCACACTTAGCAGAGAGTAGTCGTCC CSEQ ID NO: 42 GlutaCp15CTCTCGGGACGACGGCGGGGAAAGGACCCTAGTTCCTGGTGTAGTCGTCC C SEQ ID NO: 43Aptamer against Glycine-Cp*Rh complex Short binding formGACGGGCTAGGCGTGGGTGTAAAGGCACAGGGGTC SEQ ID NO: 44 Glycine-Cp*Rh_01TCGGGACGACGGGCTAGGCGTGGGTGTAAAGGCACAGGGGTCGTCCCGA SEQ ID NO: 45Gly-Cp sensor CTCTCGGGACGACGGGCTAGGCGTGGGTGTAAAGGCACAGGGGTCGTCCCSEQ ID NO: 46 Gly-Cp sensor +1 bpCTCTCGGGACGACGGGCTAGGCGTGGGTGTAAAGGCACAGGGGTCGTCCC G SEQ ID NO: 47GLYHW-Cp*Rh 06 CTCTCGGGACGACGGGTCAGTTAGACCGTGAGGCTTCCGAATAGTCGTCC CSEQ ID NO: 48 LeuCp01 CTCTCGGGACGACGGCGGGGGTCCCAGCGTTGCATGGTGTGTAGTCGTCCC SEQ ID NO: 49 LeuCp04CTCTCGGGACGACGGCGGGCGCGTGATCGGAGAGAAAGGTGTAGTCGTCC C SEQ ID NO: 50LeuCp17 CTCTCGGGACGACGGCGGGCGCGTATGTATATCATAAGGTGTAGTCGTCC CSEQ ID NO: 51 LysCp05 CTCTCGGGACGACGCGGTGTGGATCCCTCGTAGAAGGAGTAGTGTCGTCCC SEQ ID NO: 52 LysCp*Rh18CTCTCGGGACGACGGGTGGGAGCGATTCGAGCTACTCAGGTATGTCGTCC C SEQ ID NO: 53PACp*Rh01 CTCTCGGGACGACGGACGCTAATCTTACAAGGGCGTAGTGTATGTCGTCC CSEQ ID NO: 54 PACp*Rh02CTCTCGGGACGACCGCCGATAATCTCACAAGGGCGTATCAAAGGTCGTCC C SEQ ID NO: 55PACp*Rh03 CTCTCGGGACGACGGGTAGGGATGTCTAATCCCGGCGGGAGCTGTCGTCC CSEQ ID NO: 56 HPheAl04CTCTCGGGACGACCGCGTTTCCCAAGAAAGCAAGTTTTGGTTGGTCGTCC C SEQ ID NO: 57HTrp03 CTCTCGGGACGACCGCGGTAGTCTTAACCTAAAGCGGTGTCAGGTCGTCC CSEQ ID NO: 58 Aptamer against Tyrosine-Cp*Rh complex Short binding formGACGGCCCGATCTCAGAGTAGTC SEQ ID NO: 59 Tyrosine-Cp*Rh_02TCTCGGGACGACggcccgaatgtgtaagtaGTCGTCCC SEQ ID NO: 60 Tyrosine-Cp*Rh_03TCTCGGGACGACggcccgatgttccagagtaGTCGTCCC SEQ ID NO: 61 Tyrosine-Cp*Rh_04TCTCGGGACGACggcccgatgatgtattcgagtaGTCGTCCC SEQ ID NO: 62Tyrosine-Cp*Rh_05 CTCGGGACGACggcccgtagatattagtaGTCGTCCC SEQ ID NO: 63Tyrosine-Cp*Rh_06 TCTCGGGACGACggcccgcattaattagtaGTCGTCCC SEQ ID NO: 64Tyrosine-Cp*Rh_07 TCTCGGGACGACggcccgaaactgagtaGTCGTCCC SEQ ID NO: 65Tyrosine-Cp*Rh_08 TCTCGGGACGACggcccgagcactaggagtaGTCGTCCC SEQ ID NO: 66Tyrosine-Cp*Rh_09 TCTCGGGACGACggcccgatagtagagtaGTCGTCCC SEQ ID NO: 67Tyrosine-Cp*Rh_10 CTCTCGGGACGACggcccgagataatcaagtaGTCGTCCC SEQ ID NO: 68Tyrosine-Cp*Rh_11 CTCTCGGGACGACggcccgaacatatgtaagtaGTCGTCCCSEQ ID NO: 69 Tyrosine-Cp*Rh_12CTCTCGGGACGACggcccgatatgtaattagtaGTCGTCCC SEQ ID NO: 70Tyrosine-Cp*Rh_13 CTCTCGGGACGACggcccgacatcatcatcagtatatagagtaGTCGTCC CSEQ ID NO: 71 Tyr-Cp*Rh (38 nt) CTCTCGGGACGACGGCCCGATCTCAGAGTAGTCGTCCCSEQ ID NO: 72 HTyrs07 CTCTCGGGACGACCAAGCGAGTAGTAACACGGCCCGACACTGGGTCGTCCC SEQ ID NO: 73 Cu(II)_Phe01CTCTCGGGACGACGAGGCTGGATGCATTCGCCGGATGTTCGATGTCGTCC C SEQ ID NO: 74Cu(II)-Phe10 CTCTCGGGACGACAAGGTCCCTTTCGTAGATCGAGGAAGTATTGTCGTCC CSEQ ID NO: 75 Cu(II)-Phe10_49ntCTCTCGGGACGACAGGTCCCTTTCGTAGATCGAGGAAGTATGTCGTCCC

What is claimed is:
 1. A method for isolating an aptamer specific for acomplex comprising a target molecule, the method comprising: providing atarget molecule; providing a derivatization agent; contacting the targetmolecule and the derivatization agent to form a target complex;providing an oligonucleotide library comprising a plurality of aptamercandidates; contacting the target complex and the oligonucleotidelibrary; and isolating an aptamer that binds to the target complex. 2.The method of claim 1, wherein isolating the aptamer that binds to thetarget complex comprises removal of aptamer candidates that do not bindto the target complex.
 3. The method of claim 2, further comprising:eluting the aptamer from the bound target complex under increasingstringency; and isolating an eluted aptamer having high affinity for thetarget complex.
 4. The method of claim 1, comprising systematicevolution of ligands by exponential enrichment (SELEX).
 5. The method ofclaim 1, wherein the aptamer does not substantially bind thenon-complexed target molecule.
 6. The method of claim 1, wherein theaptamer does not substantially bind the non-complexed derivatizationagent.
 7. The method of claim 1, further comprising counter-selecting anaptamer against the derivatization agent alone or against the targetmolecule alone.
 8. The method of claim 1, wherein the oligonucleotidelibrary comprises randomly generated oligonucleotide sequences of afixed length flanked by a constant 5′ end and a constant 3′ end, theconstant 5′ end and the constant 3′ end functioning as a primer.
 9. Themethod of claim 1, wherein the aptamer is a DNA, RNA, or XNA molecule.10. The method of claim 1, wherein the aptamer comprises at least about15 oligonucleotides up to about 100 oligonucleotides.
 11. The method ofclaim 1, wherein the aptamer comprises equilibrium constant (K_(d)) ofabout 1 pM up to about 10.0 μM; about 1 pM up to about 1.0 μM; about 1pM up to about 100 nM; about 100 pM up to about 10.0 μM; about 100 pM upto about 1.0 μM; about 100 pM up to about 100 nM; or about 1.0 nM up toabout 10.0 μM; about 1.0 nM up to about 1.0 μM; about 1 nM up to about200 nM; about 1.0 nM up to about 100 nM; about 500 nM up to about 10.0μM; or about 500 nM up to about 1.0 μM.
 12. The method of claim 1,wherein the target molecule comprises a small molecule, a protein, or anucleic acid.
 13. The method of claim 1, wherein the target moleculecomprises a small molecule selected from the group consisting of acarbohydrate molecule, a fatty acid molecule, a steroid molecule, anamino acid, a lead-like small molecule, a drug-like small molecule, anda derivative or a combination thereof.
 14. The method of claim 1,wherein the target molecule comprises a carbohydrate molecule selectedfrom the group consisting of glucose, dextrose, fructose, galactose,sucrose, maltose, lactose, polyol, polyhydric alcohol, polyalcohol,glycitol, methanol, glycol, glycerol, erythritol, threitol, arabitol,xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol,inositol, volemitol, isomalt, maltitol, lactitol, maltotriitol,maltotetraitol, and polyglycitol.
 15. The method of claim 1, wherein thetarget molecule comprises a lipid molecule selected from the groupconsisting of a fatty acid, a steroid, a sphingolipid, or aphospholipid.
 16. The method of claim 1, wherein the target moleculecomprises a steroid molecule selected from the group consisting of acaprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,stearic acid, arachidic acid, behenic acid, lignoceric acid, ceroticacid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid,elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid,a-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid,and docosahexaenoic acid, cholestane, a cholane, a pregnane, anandrostane, a gonane, an estrane, cholesterol, estradiol, testosterone,progesterone, medrogestone, β-sitosterol, dexamethasone,sphingosine-phosphate, sphingomyeline, ganglioside, andphosphatidyl-choline, or derivatives thereof.
 17. The method of claim 1,wherein the target molecule comprises an amino acid selected from thegroup consisting of histidine, isoleucine, leucine, lysine, methionine,phenylalanine, threonine, tryptophan, valine, alanine, arginine,asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine,proline, serine, tyrosine, selenocysteine, pyrrolysine, lanthionine,2-aminoisobutyric acid, dehydroalanine, N-formylmethionine,gamma-amino-butyric acid (GABA), hydroxyproline, carnitine, ornithine,S-adenosylmethionine, citrulline, beta alanine (3-aminopropanoic acid),canavanine, mimosine, aspartame, 5-hydroxytryptophan,L-dihydroxyphenylalanine, and eflornithine.
 18. The method of claim 1,wherein the derivatization agent comprises a metal ion complex, a cyclicoligosaccharide, or a boronic acid.
 19. The method of claim 1, wherein:the target molecule comprises an amino acid and the derivatization agentcomprises a metal ion complex; the target molecule comprises a fattyacid, a steroid, a hydrophobic lead-like compound, or a hydrophobicdrug-like compound and the derivatization agent comprises a cyclicoligosaccharide; or the target molecule comprises a carbohydrate and thederivatization agent comprises a boronic acid.
 20. The method of claim1, wherein the derivatization agent comprises Cp*Rh(III) or a metal ioncomplex selected from Ni(II), Cu(II), Zn(II), or Co(III) bound to abidentate, tridentate, or tetradentate ligand.
 21. The method of claim1, wherein the derivatization agent comprises a cyclic oligosaccharide,the cyclic oligosaccharide comprising a cyclodextrin derivative.
 22. Themethod of claim 1, wherein the derivatization agent comprises a boronicacid, the boronic acid comprising a bis-boronic acid, an aromaticboronic acid, an amino boronic acid, or an aromatic amino boronic acid.23. The method of claim 1, wherein isolating an aptamer that binds tothe target complex comprises: isolating an aptamer that binds to thetarget complex and has a nucleic acid sequence comprising one or moreunpaired nucleic acid bases when the aptamer is folded into a doublestranded configuration, wherein the one or more unpaired nucleic acidbases form a binding pocket such that the aptamer can bind thederivatization agent and the target molecule.
 24. An aptamer selectedfrom the group consisting of: (a) an aptamer selected according to themethod of claim 1; (b) an aptamer comprising SEQ ID NO: 3; SEQ ID NO: 4(Glucose-BA_01); SEQ ID NO: 5 (Glucose-BA_07); SEQ ID NO: 6(Glucose-BA_08); SEQ ID NO: 7 (Glucose-BA_09); SEQ ID NO: 8(Glucose-BA_10); SEQ ID NO: 9 (Glucose-BA_11); SEQ ID NO: 10(Glucose-BA_12); SEQ ID NO: 11 (Glucose-BA_13); SEQ ID NO: 12(Glucose-BA_14); SEQ ID NO: 13 (Glucose-BA_15); SEQ ID NO: 14(Glucose-BA_16); SEQ ID NO: 15 (Glucose-BA_17); SEQ ID NO: 16 (GLUBA02);SEQ ID NO: 17 (GLUBA09); SEQ ID NO: 18 (GLUBA09_M1); SEQ ID NO: 19(GLUBA17); SEQ ID NO: 20 (GLUBAN3W10); SEQ ID NO: 21 (GLUBAN3W11); orSEQ ID NO: 22 (GLUBAN3W19), or a sequence at least 90% identical theretoand binding glucose complexed with a bis-boronic derivatization agent;(c) an aptamer comprising SEQ ID NO: 23 (FrucBA02); SEQ ID NO: 24(FrucBA02_M1); or SEQ ID NO: 25 (FrucBA05), or a sequence at least 90%identical thereto and binding fructose complexed with a bis-boronicderivatization agent; (d) an aptamer comprising: SEQ ID NO: 26(GalacBA05); SEQ ID NO: 27 (GalacBA01); or SEQ ID NO: 28 (GalacBA06), ora sequence at least 90% identical thereto and binding galactosecomplexed with a bis-boronic derivatization agent. (e) an aptamercomprising SEQ ID NO: 29 (BAOnly01); or SEQ ID NO: 30 (BAOnly03), or asequence at least 90% identical thereto and binding boronic acid; (f) anaptamer comprising SEQ ID NO: 31; SEQ ID NO: 32 (Arginine-Cp*Rh_02); SEQID NO: 33 (Arginine-Cp*Rh_03); SEQ ID NO: 34 (Arginine-Cp*Rh_04); SEQ IDNO: 35 (Arginine-Cp*Rh_05); or SEQ ID NO: 36 (ARG01_Cp), or a sequenceat least 90% identical thereto and binding arginine complexed with aCp*Rh(III) derivatization agent; (g) an aptamer comprising SEQ ID NO: 37(AspaCp01); SEQ ID NO: 38 (AspaCp03); or SEQ ID NO: 39 (AspaCp04), or asequence at least 90% identical thereto and binding asparagine complexedwith a Cp*Rh(III) derivatization agent; (h) an aptamer comprising SEQ IDNO: 40 (CIT30NO2_Cp*Rh), or a sequence at least 90% identical theretoand binding citrulline complexed with a Cp*Rh(III) derivatization agent;(i) an aptamer comprising SEQ ID NO: 41 (GlutaCp02); or SEQ ID NO: 42(GlutaCp15), or a sequence at least 90% identical thereto and bindingglutamine complexed with a Cp*Rh(III) derivatization agent; (j) anaptamer comprising SEQ ID NO: 43; SEQ ID NO: 44 (Glycine-Cp*Rh_01); SEQID NO: 45 (Gly-Cp); SEQ ID NO: 46 (Gly-Cp+1 bp); or SEQ ID NO: 47(GLYHW-Cp*Rh 06), or a sequence at least 90% identical thereto andbinding glycine complexed with a Cp*Rh(III) derivatization agent; (k) anaptamer comprising SEQ ID NO: 48 (LeuCp01); SEQ ID NO: 49 (LeuCp04); orSEQ ID NO: 50 (LeuCp17), or a sequence at least 90% identical theretoand binding leucine complexed with a Cp*Rh(III) derivatization agent;(l) an aptamer comprising SEQ ID NO: 51 (LysCp05); or SEQ ID NO: 52(LysCp*Rh18), or a sequence at least 90% identical thereto and bindinglysine complexed with a Cp*Rh(III) derivatization agent; (m) an aptamercomprising SEQ ID NO: 53 (PACp*Rh01); SEQ ID NO: 54 (PACp*Rh02); SEQ IDNO: 55 (PACp*Rh03); or SEQ ID NO: 56 (HPheAl04), or a sequence at least90% identical thereto and binding phenylalanine complexed with aCp*Rh(III) derivatization agent; (n) an aptamer comprising SEQ ID NO: 73(Cu(II)_Phe01); SEQ ID NO: 74 (Cu(II)-Phe10); or SEQ ID NO: 75(Cu(II)-Phe10_49 nt), or a sequence at least 90% identical thereto andbinding phenylalanine complexed with a Cu(II) derivatization agent; (o)an aptamer comprising SEQ ID NO: 57 (HTrp03), or a sequence at least 90%identical thereto and binding tryptophan complexed with a Cp*Rh(III)derivatization agent; (p) an aptamer comprising SEQ ID NO: 57 (HTrp03),or a sequence at least 90% identical thereto and binding tryptophancomplexed with a Cp*Rh(III) derivatization agent; or (q) an aptamercomprising SEQ ID NO: 58; SEQ ID NO: 59 (Tyrosine-Cp*Rh_02); SEQ ID NO:60 (Tyrosine-Cp*Rh_03); SEQ ID NO: 61 (Tyrosine-Cp*Rh_04); SEQ ID NO: 62(Tyrosine-Cp*Rh_05); SEQ ID NO: 63 (Tyrosine-Cp*Rh_06); SEQ ID NO: 64(Tyrosine-Cp*Rh_07); SEQ ID NO: 65 (Tyrosine-Cp*Rh_08); SEQ ID NO: 66(Tyrosine-Cp*Rh_09); SEQ ID NO: 67 (Tyrosine-Cp*Rh_10); SEQ ID NO: 68(Tyrosine-Cp*Rh_11); SEQ ID NO: 69 (Tyrosine-Cp*Rh_12); SEQ ID NO: 70(Tyrosine-Cp*Rh_13); SEQ ID NO: 71 (Tyr-Cp*Rh (38nt)); or SEQ ID NO: 72(HTyrs07), or a sequence at least 90% identical thereto and bindingtyrosine complexed with a Cp*Rh(III) derivatization agent.
 25. Theaptamer of claim 24, wherein: the aptamer has a nucleic acid sequencecomprising one or more unpaired nucleic acid bases when the aptamer isfolded into a double stranded configuration; the one or more unpairednucleic acid bases form a binding pocket such that the aptamer can binda derivatization agent and a target molecule; and the aptamer comprisesSEQ ID NO: 71 (Tyr-Cp*Rh(38nt)); SEQ ID NO: 53 (PACp*Rh01); SEQ ID NO:40 (CIT30NO2_Cp*Rh); SEQ ID NO: 41 (GlutaCp02); SEQ ID NO: 52(LysCp*Rh18); SEQ ID NO: 51 (LysCp05); SEQ ID NO: 75 (Cu(II)-Phe10_49nt); SEQ ID NO: 36 (ARG01_Cp); SEQ ID NO: 57 (HTrp03 aptamer); SEQ IDNO: 45 (Gly-Cp); SEQ ID NO: 38 (AspaCp03); SEQ ID NO: 47(GLYHW-Cp*Rh06); SEQ ID NO: 50 (LeuCp17); SEQ ID NO: 53 (PACp*Rh01); SEQID NO: 73 (Cu(II)_Phe01); or SEQ ID NO: 56 (HPheAl04); or a sequence atleast 90% identical thereto and binding the target molecule complexedwith the derivatization agent.
 26. A method of detecting a targetmolecule in a sample, the method comprising: (a) providing a sample; (b)contacting the biological sample and a derivatization agent to form atarget complex comprising the derivatization agent and a target moleculewhen the target molecule is present in the sample; (c) contacting thebiological sample and (i) an aptamer selected according to the method ofclaim 1 or (ii) an aptamer according to claim 24 to form anaptamer-target complex when the target complex is present in the sample;and (d) detecting the aptamer-target complex when present in the sample.